Mechanism for moving optical element of an optical system

ABSTRACT

First lens frame has first front and rear shaft bearings that engage with the first guiding shaft along the optical axis, and a second shaft bearing that engages with a second guiding shaft along the optical axis. The first front and rear shaft bearings are spaced apart from each other along the first guiding shaft. Second lens frame has third front and rear shaft bearings that engage with the second guiding shaft, spaced apart form each other, and fourth shaft bearing that engages with the first guiding shaft. The third front and rear shaft bearings are arranged with the second shaft bearing between them, and fourth shaft bearing is disposed between the first front and second shaft bearings.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a mechanism for moving opticalelements of an optical system along the optical axis.

[0002] There are optical systems provided with zooming functions, suchas some kind of binoculars. Such optical systems vary themagnifying-power by moving two optical lenses, for example, and changethe distance between them in the optical axis direction. A lens movingmechanism, used in such optical system to move the lenses along theoptical axis, is provided with two lens frames, each for supporting oneof the two lenses, and two guiding shafts along which the lens framesmove. The guiding shafts are disposed at both side of the lens framesand extending parallel to the optical axes. The guiding shafts areinserted in holes formed on each sides of each lens frame. Thus, eachlens frame engages with the guiding shafts slidably so that it canslide, and therefore move the lenses, along the guiding shafts, i.e.parallel to the optical axis.

[0003] It is necessary for the lens frames to have the holes forreceiving the guiding shafts as long as possible so that each lens framecan be guided precisely without play along the guiding shaft. However,such long holes require longer size of the lens frame along the guidingshafts, which make it difficult to produce a compact lens movingmechanism.

SUMMARY OF THE INVENTION

[0004] It is therefore an object of the invention to provide a compactmechanism for moving optical elements of an optical system.

[0005] A mechanism according the invention is for moving a first opticalelement and a second optical element along an optical axis of an opticalsystem. The mechanism comprises first and second guiding shafts, a firstframe, and a second frame.

[0006] The first and second guiding shafts are disposed parallel to theoptical axis and spaced apart to each other in a direction perpendicularto the optical axis.

[0007] The first frame is movable along the optical axis and supportsthe first optical element. The first frame includes first front and rearshaft bearings and a second shaft bearing. The first front and rearshaft bearings are disposed spaced apart from each other along the firstguiding shaft and are engaged with the first guiding shaft slidablyalong the longitudinal direction of the first guiding shaft. The secondshaft bearing is engaged with the second guiding shaft slidably alongthe longitudinal direction of the second guiding shaft. It should benoted that a shaft “bearing” as described herein includes any kind ofshaft receiving structure that supports and/or guides thesupported/guided element having the bearing along a shaft (includingslide, plain, journal, roller/ball bearings and bushings). The shaftsdiscussed herein need not have a circular cross section.

[0008] The second frame is movable along the optical axis and supportsthe second optical element. The second frame includes third front andrear shaft bearings and a fourth shaft bearing. The third front and rearshaft bearings are disposed spaced apart from each other along thesecond guiding shaft with the second shaft bearing therebetween and areengaged with the second guiding shaft slidably along the longitudinaldirection of the second guiding shaft. The fourth shaft bearing isengaged with the first guiding shaft slidably along the longitudinaldirection of the first guiding shaft between the first front and rearshaft bearings.

[0009] The first front and rear shaft bearings may be provided with afirst front hole and a first rear hole, respectively, into which thefirst guiding shaft is to be inserted. Preferably, the first front andrear holes are formed to receive the first guiding shaft without playwithin a plane perpendicular to the optical axis. The second shaftbearing maybe provided with a second hole, into which the second guidingshaft is inserted, formed to receive the second guiding shaft with playin a direction substantially perpendicular to the optical axis (e.g.,horizontal). For example, the second hole may have a rectangularcross-section of which longitudinal axis is perpendicular to the firstguiding shaft.

[0010] The third front and rear shaft bearings may be provided with athird front hole and a third rear hole, respectively, into which thesecond guiding shaft is inserted. The third front and rear holes areformed to receive the second guiding shaft without play within a planeperpendicular to the optical axis. The fourth shaft bearing is providedwith a fourth hole, into which the first guiding shaft is inserted,formed to receive the first guiding shaft with play in a directionsubstantially perpendicular to the optical axis (e.g., horizontal). Forexample, the fourth hole may have a rectangular cross-section of whichlongitudinal axis is perpendicular to the second guiding shaft.

[0011] The first frame may have a first extension extending parallel tothe first guiding shaft between the first front and rear shaft bearingsto support the second rear shaft bearing spaced apart from the firstfront shaft bearing. Preferably, the first extension has an abuttingportion against which the fourth shaft bearing abuts to align the fourthhole with the first front hole and the first rear hole.

[0012] The second frame may have a second extension extending parallelto the second guiding shaft between the third front and rear shaftbearings to support the third rear shaft bearing spaced apart from thethird front shaft bearing.

[0013] Preferably, the second extension has an abutting portion againstwhich the second shaft bearing abuts to align the second hole with thethird front hole and the third rear hole.

[0014] The first and second guiding shafts are preferably arranged on aplane including the optical axis. Further, each of the first and secondoptical elements is preferably an optical lens. Further preferably, thefirst and second optical elements are lenses of a telescope opticalsystem of which magnifying power varies when distance between the firstand second optical elements along the optical axis is changed.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0015] The present invention is further explained in the descriptionwhich follows with reference to the drawings, illustrating, by way ofnon-limiting examples, various embodiments of the invention, with likereference numerals representing similar parts throughout the severalviews.

[0016]FIG. 1A shows a plan view of a binocular to which a lens movingmechanism according to an embodiment of the invention is applied, inwhich right and left lens barrels are in contact with each other, andright and left eyepiece barrels are contained inside a binocular body;

[0017]FIG. 1B shows a front view of the binocular of FIG. 1A seen fromthe direction of an arrow A1; and

[0018]FIG. 1C shows a side view of the binocular of FIG. 1A seen fromthe direction of an arrow A2.

[0019]FIG. 2A shows a bottom plan view of the binocular of FIG. 1A; and

[0020]FIG. 2B shows a rear plan view of FIG. 2A, seen from the directionof an arrowA3, of the binocular at the same configuration with FIG. 1.

[0021]FIG. 3A shows an upper plan view of the binocular to which a lensmoving mechanism according to an embodiment of the invention is applied,in which the right and left lens barrels are moved apart from each otheras much as is permitted by the mechanisms described herein, and in whichthe right and left eyepiece lens barrels are drawn from the respectivelens barrels by as much as is permitted by the mechanisms describedherein;

[0022]FIG. 3B shows a front view of the configuration of FIG. 3A seenfrom the direction of arrow B1;

[0023]FIG. 3C shows a side view of the configuration of FIG. 3A seenfrom the direction of an arrow B2; and

[0024]FIG. 3D shows a side view of the configuration of FIG. 3A seenfrom the direction of an arrow B3.

[0025]FIG. 4A shows a bottom plan view of the binocular in the sameconfiguration as FIGS. 3A through 3D;

[0026]FIG. 4B shows a back view of the configuration of FIG. 4A seenfrom the direction of an arrow B4; and

[0027]FIG. 4C shows a side view of the configuration of FIG. 4A seenfrom the direction of an arrow B5.

[0028]FIG. 5 shows a partially cross-sectional top plan view of thebinocular.

[0029]FIG. 6 shows a cross-sectional view of FIG. 5 taken along a lineVI-VI.

[0030]FIG. 7 shows an exploded perspective view, illustrating anoverview of the binocular.

[0031]FIG. 8 shows an exploded perspective view, illustrating a portionof a supporting member shown in FIG. 7.

[0032]FIG. 9 shows an exploded perspective view, illustrating a portionof an optical operating unit and a supporting unit shown in FIG. 7.

[0033]FIG. 10 shows an exploded perspective view, illustrating thestructure of the optical operating unit shown in FIG. 7.

[0034]FIG. 11 shows an exploded perspective view, illustrating astructure of a portion of the optical operating unit and an upper plateshown in FIG. 7.

[0035]FIG. 12 shows an exploded perspective view, illustrating at leasta right outer unit of a right lens barrel.

[0036]FIG. 13 shows an exploded perspective view, illustrating at leasta right moving unit, a right objective unit and a right prism unit ofthe right lens barrel.

[0037]FIG. 14 shows an exploded perspective view, illustrating at leasta first lens unit, a second lens unit and an eyepiece unit of the rightlens barrel.

[0038]FIG. 15 shows an exploded perspective view, illustrating at leasta left outer unit of the left lens barrel.

[0039]FIG. 16 shows an exploded perspective view, illustrating at leastthe objective unit, the first lens unit and the second lens unit of theleft lens barrel.

[0040]FIG. 17 shows an exploded perspective view, illustrating at leastthe first lens unit, the second lens unit and the eyepiece unit of theleft lens barrel.

[0041]FIG. 18 shows a bottom view of the binocular, with a “zero point”mark of a diopter decorative ring being aligned with a reference mark.

[0042]FIG. 19 shows a bottom view of the binocular with a positive “+”mark of the diopter decorative ring being aligned with the referencemark.

[0043]FIG. 20 shows a bottom plan view of the binocular with a negative“−” mark of the diopter decorative ring being aligned with the referencemark.

[0044]21A shows a partially sectioned top plan view of the left lensbarrel; and

[0045]FIG. 21B shows an enlarged cross sectional view of a part of theleft lens barrel.

[0046]FIG. 22 is an enlarged cross sectional view of the left lensbarrel of FIG. 21A, illustrating an operation of a diopter correction ona production/manufacturing or assembly-time stage.

[0047]FIG. 23 is an enlarged perspective view of a bottom lid.

[0048]FIGS. 24A, 24B, and 24C are orthogonal views of the bottom lid ofFIG. 23, showing top, side center section, and bottom views,respectively; and FIG. 24D shows four cross sections taken through FIG.24B.

[0049]FIGS. 25A and 25B are perspective views of a diopter eccentricseat and diopter decorative ring, respectively.

[0050]FIGS. 26A, 26B, and 26C are orthogonal views of the diopterdecorative ring of FIG. 25B, showing top, side, and bottom views,respectively.

[0051]FIGS. 27A, 27B, and 27C are orthogonal views of the dioptereccentric seat of FIG. 25A, showing top, side, and bottom views,respectively.

[0052]FIG. 28 shows a front view of a first lens frame.

[0053]FIG. 29 shows a rear view of the first lens frame.

[0054]FIG. 30 shows a top plan view of the first lens frame.

[0055]FIG. 31 shows a cross-sectional view of FIG. 28 along a lineC1-C1.

[0056]FIG. 32 shows a cross-sectional view of FIG. 30 along a lineC2-C2.

[0057]FIG. 33 shows a front view of a second lens frame.

[0058]FIG. 34 shows a rear view of the second lens frame.

[0059]FIG. 35 shows a cross-sectional view of FIG. 33 along a lineD1-D1.

[0060]FIG. 36 shows a side view of FIG. 33 seen in an arrow D2direction.

[0061]FIG. 37 shows a cross-sectioned view, illustrating substantialparts of FIG. 36 viewed along a line D3-D3.

[0062]FIG. 38 shows a plan view, illustrating the first and second lensframes coupled to a first and second guiding shafts.

[0063]FIG. 39 shows a front view, illustrating the first and second lensframes coupled to the first and second guiding shafts.

[0064]FIG. 40 shows a back view, illustrating the first and second lensframes coupled to the first and second guiding shafts.

[0065]FIG. 41 shows a bottom view, illustrating the first and secondlens frame coupled to the first and second guiding shafts.

[0066]FIG. 42 shows a bottom plan view illustrating an opticalarrangement unit, in which the first and second lens sliders aredisposed apart farthest from each other for setting a magnifying powerto a lowest magnification.

[0067]FIG. 43 shows a bottom plan view illustrating an opticalarrangement unit, in which the first and second lens sliders aredisposed nearest to each other for setting the magnifying power to ahighest magnification.

DESCRIPTION OF THE EMBODIMENTS

[0068] Hereinafter, referring to the accompanying drawings, embodimentsaccording to the present invention will be described.

[0069] In the description, an objective side along an optical axis iscalled a “front side”, and an eyepiece side is called a “rear side”. Theterms “frontward” and “rearward” means respectively “toward the frontside” and “toward the rear side”. Right and left directions of thebinocular are defined by the orientations mentioned above, that is, theright and left sides of the binocular as used herein corresponds to thesides that a user of the binocular would consider his or her right andleft sides when operating the binocular. In general, as used herein, the“length” direction is front to back or vice versa, the “width” directionis left to right or vice versa, and the “height” direction is top tobottom or vice versa.

[0070] First, referring to FIGS. 1 and 2, an overview of the binocularwill now be described.

[0071] A binocular 1000 includes a supporting unit 100 (see FIG. 3), anoptical operating unit 200, the right lens barrel 300 and the left lensbarrel 400.

[0072] The supporting unit 100 is provided between the right and leftlens barrels (300, 400), for supporting the right and left lens barrels(300, 400). The right and left lens barrels (300, 400) have respectivetelescope optical systems therein.

[0073] There are provided, at the supporting unit 100, a diopterdecorative ring 106 and an optical operating unit 200. The diopterdecorative ring 106 is provided on the bottom surface of the supportingunit 100, the surface of the diopter decorative ring 106 being exposed,i.e., facing outward. The optical operating unit 200 includes a focusarrangement ring 202 for arranging or adjusting focus of the binocular,and a zooming operation ring 204 for setting and adjustingmagnifying-power of both of the right and left telescope opticalsystems.

[0074] The right and left lens barrels (300, 400) are supported by thesupporting unit 100 therebetween, and are movable in the width directionof the binocular 1000, or the lateral direction. The right lens barrel300 and the left lens barrel 400 cooperate to simultaneously movesymmetrically with respect to the center line of the supporting unit.

[0075] The right and left lens barrels (300, 400) include respectively aright moving unit 303 (shown in FIG. 5) and a left moving unit 403(shown in FIG. 7), and respectively a right eyepiece cylinder 304 and aleft eyepiece cylinder 404 (each shown in FIG. 7). The right moving unit303 holds a right eyepiece lens unit 309 and a right erecting prism unit306. The left moving unit 403 holds a left eyepiece lens unit 409 and aleft erecting prism unit 406.

[0076] If the focus arrangement ring 202 is rotated, the right and leftmoving unit (303, 304) and the right and left eyepiece cylinder (304,404) are moved for focus arrangement.

[0077] If the zooming operation ring 204 is rotated, portions of theoptical structure, included both in the right and left lens barrel (300,400) and as described herein, are moved along the optical axis forvarying the magnifying-power.

[0078] The focus arrangement ring 202 and the zooming arrangement ring204 are disposed near to the rear end (i.e., near to the eyepiececylinder) of the binocular 1000 along the center line. The focusarrangement ring 202 and the zooming arrangement ring 204 are coaxialand adjacent to one another, in this order from the front end, and areeach rotatable about an axis parallel to the optical axes. The focusarrangement ring 202 and the zooming arrangement ring 204 are disposedfacing outward from the upper surface of the supporting unit 100.

[0079] The diopter decorative ring 106 is disposed on the bottom frontsurface of the supporting unit 100 of the binocular 1000. The diopterdecorative ring 106 is exposed, i.e., faces outward, from the bottomsurface and is located along the center line mentioned above.

[0080] Therefore, when an observer or user holds the binocular, theright and left lens barrels are held by the operator's hands so that thediopter decorative ring 202 can be operated by fingers of either hand.Since the focus arrangement ring 202 and the zooming arrangement ring204 are disposed on the center line, whichever hand can operate therings more easily for more comfortable operation of the binocular may beused by the operator.

[0081] As shown in FIGS. 18 through 20, indicia including a “zero point”mark 106F, a “plus” mark 106G and a “minus” mark 106H are marked on thesurface of the diopter decorative ring 106, which can be seen from theoutside of the binocular by the operator. The “zero point” mark 106F,when aligned with a reference mark 102L on the supporting unit 100,indicates no diopter difference (i. e. the zero point), and the“plus”/“minus” marks illustrate the direction of the diopter correctionto be made, the “plus” and “minus” marks optionally indicating the endof the adjustment range.

[0082] In the following description, the structures of each operationalunit of the binocular 1000 are described.

[0083]FIG. 5 shows a partially cross-sectioned top plan view of thebinocular 1000, FIG. 6 shows a cross-sectioned view of FIG. 5 along aline VI-VI of FIG. 5, and FIG. 7 shows an exploded perspective viewillustrating an overview of the binocular assembly.

[0084]FIG. 8 shows an exploded perspective view illustrating a portionof a supporting member, FIG. 9 shows an exploded perspective viewillustrating a portion of an optical operating unit and the supportingunit, FIG. 10 shows an exploded perspective view illustrating thestructure of the optical operating unit, and FIG. 11 shows an explodedperspective view illustrating a structure of a portion of the opticaloperating unit and an upper plate.

[0085]FIG. 12 shows an exploded perspective view illustrating mainly astructure of a right outer unit of the right lens barrel. FIG. 13 showsan exploded perspective view illustrating mainly a structure of a rightmoving unit, a right objective unit and a right prism unit of the rightlens barrel, FIG. 14 shows an exploded perspective view illustratingmainly a structure of a first lens unit, a second lens unit and aneyepiece unit of the right lens barrel.

[0086]FIG. 15 shows an exploded perspective view illustrating mainly astructure of a left outer unit of the left lens barrel, FIG. 16 shows anexploded perspective view mainly of the structure of the objective unit,the first lens unit and the second lens unit of the left lens barrel,FIG. 17 shows an exploded perspective view of mainly the structure ofthe first lens unit, the second lens unit and the eyepiece unit of theleft lens barrel.

[0087] Referring to the FIGS. 7 to 11, the structures of the supportingunit 100 and the optical operating unit will now be described.

[0088] As shown in FIGS. 7 through 11, the supporting unit 100 includesa body 101 (shown in FIGS. 9 and 10), a supporting plate 102 (shown inFIGS. 7 and 8), a bottom lid 103 (shown in FIGS. 7 through 9), an upperplate 104 (shown in FIGS. 7 and 11), a pinion gear 105, a rightcooperation plate 109, a left cooperation plate 110 and other parts asdescribed below. The bottom lid 103 is provided with the diopterdecorative ring 106 and a diopter arranging eccentric seat 107 thatconstitute the diopter correction unit, which is described below.

[0089] The supporting plate 102 is formed in a generally rectangularshape, and has longitudinal sides that are substantially parallel to afront and a rear edge lines of the binocular 1000. The right and leftsides of the supporting plate 102 are parallel to the right and leftsides of the binocular 1000.

[0090] As shown in FIG. 8, two protrusions 102A1 and 102A2 are formeddisposed in the vicinity of the upper right edge portion, near to thefront corner and rear corner, respectively, of the supporting plate 102.Similarly, two protrusions 102B1 and 102B2 are formed disposed in thevicinity of the upper left edge portion, near to the front corner andrear corner, respectively, of the supporting plate 102.

[0091] Two protrusion 102B3 and 102A3 are formed in this order from thefront side of the supporting plate 102 and projecting therefrom, andpositioned approximately on the binocular center line between thelateral sides on the supporting plate 102. A circular opening 102C isformed between the front protrusion 102B3 and the front edge, and athreaded hole 102D is formed (penetrating the supporting plate 102)between the two protrusions 102B3 and 102A3.

[0092] Two engaging grooves 102H1 and 102I1 are formed (penetrating thesupporting plate 102 in the height direction), extending near to andparallel to the front edge of the supporting plate 102. The engaginggroves 102H1 and 102I1 are formed symmetrically with respect to thecenter of the width of the binocular 1000. Similarly, two engaginggrooves 102H2 and 102I2 are formed (penetrating the supporting plate 102in the height direction), extending near to and parallel to the rearedge of the supporting plate 102. The engaging groves 102H2 and 102I2are also formed symmetrically with respect to the center of the width ofthe binocular 1000.

[0093] Two notches 102J1 and 102J2 are cut disposed at a predetermineddistance along the right edge of the supporting plate 102, near to thefront and rear edge, respectively, and opening to the right. Two notches102K1 and 102K2 are provided similarly at the left edge disposed at apredetermined distance along the left edge of the supporting plate 103and opening to the left.

[0094] A right slide plate 109 includes a rectangular body 109A, and anextending member 109B extending from the rectangular body 109A. Twoguiding grooves 109A1 and 109A2 are formed near to front and rear edgeof the rectangular body 109A, extending in the width or lateraldirection, so as to receive the projections 102A1 and 102A2 penetratingtherethrough. A guiding groove 109B1 is formed on the extending member109B, extending laterally, to receive the projection 102A3 penetratingtherethrough.

[0095] Two threaded holes 109C1 and 109C2 are provided, penetrating theright slide plate 109, respectively positioned at the front and rearcorners of the left side of the body 109A of the right slide plate 109,and two threaded holes 109D1 and 109D2 are provided, penetrating theright slide plate 109, respectively positioned at the front and rearcorners of the right side of the body 109A of the right slide plate 109.The threaded holes 109C1 and 109C2 are disposed with the same distancetherebetween as is between the guiding grooves 102H1 and 102H2, and thethrough-hole 109D1 and 109D2 are disposed with the same distancetherebetween as is between the notches 102J1 and 102J2 on the supportingplate.

[0096] The left slide plate 110 includes a rectangular body 110A, and anextending member 110B extending from the rectangular body 110A. Twoguiding grooves 110A1 and 110A2 are formed near to the front and rearedges of the rectangular body 110A, extending laterally or in the widthdirection, so as to receive the projections 102B1 and 102B2 penetratingtherethrough. A guiding groove 110B1 is formed on the extending member110B, extending laterally, to receive the projection 102A3 penetratingtherethrough.

[0097] Two threaded holes 110C1 and 110C2 are provided, penetrating theleft slide plate 110, respectively positioned at the front and rearcorners of the left side of the body 110A of the left slide plate 110,and two threaded holes 110D1 and 110D2 are provided, penetrating theleft slide plate 110, respectively positioned at the front and rearcorners of the left side of the body 110A of the left slide plate 110.The threaded holes 110C1 and 110C2 are disposed with the same distancetherebetween as is between the guiding grooves 102I1 and 102I2, and thethrough-hole 110D1 and 110D2 are disposed with the same distancetherebetween as is between the notches 102K1 and 102K2 on the supportingplate.

[0098] A right rack 109B2 and a left rack 110B2 are providedrespectively at the front edge of the extending member 109B of the rightslide plate 109, and at the rear edge of the extending member 110B ofthe left slide plate 110. the right rack 109B2 and left rack 110B2extend laterally, in the width direction, toward the center of thebinocular 1000.

[0099] The right slide plate 109 is slidably supported on the supportingplate 102, with each guiding grooves 109A, 109A2 and 109B1 havinginserted therethrough, respectively, the projections 102A1, 102A2 and102A3, each of which has a threaded hole formed thereon. In this manner,screws 802 are engaged to the threaded holes having intervening washers801.

[0100] The left slide plate 110, similarly, has the guiding groove110A1, 110A2 and 110B1 having inserted therethrough, respectively, theprojections 102B1, 102B2 and 102B3 each of which has a screw engaging athreaded hole and intervening washers 801.

[0101] A pinion gear 105 is disposed between the right and left rack109B2, 110B2 so as to mesh with the two racks 109B2, 110B2. The shaftportion of a screw 803 penetrates the threaded hole 102D on thesupporting plate 102 from the underside thereof, and also penetrates acenter hole of the gear 105, ultimately engaging a threaded hole 103A ofthe bottom lid 103.

[0102] The position and arrangement of the bottom lid 103 are shown inFIGS. 7 and 8, while FIG. 23 is an enlarged perspective view of thebottom lid 103. Further, FIGS. 24A, 24B, and 24C are orthogonal views ofthe bottom lid of FIG. 23, showing top, side center section, and bottomviews, respectively, while FIG. 24D shows cross sections taken throughFIG. 24B. In particular, from top to bottom, FIG. 24D shows across-section through threaded hole 103A; a cross section through aposition between two protrusions 103D; a cross section through aprotrusion 103D; and a cross section through-hole 103G. The bottom lid103 is a rectangular-shaped plate, having a longitudinal direction beingextending in the optical direction, and being supported above thesupporting plate 102. The bottom lid 103 and the supporting plate 102are positioned on either side (top and bottom, respectively) of theextending portion 109B of the right slide plate 109 and the extendingportion 110B of the left slide plate 110. Further, the bottom lid 103 ispositioned between the under surface of the body 101 and upper surfaceof the supporting plate 102 in a manner detailed below.

[0103] The position of bottom lid 103 with respect to the supportingplate 102 is determined as described herein. Edge portions 103B (theright side edge portion 103B being hidden in FIGS. 8 and 23, but visiblein FIG. 24C) formed on the right and left front edges are inserted intothe grooves 102E extending along the optical direction, on both rightand left edges of the supporting plate 102. Accordingly, notches 103Cformed at the rear right and left edges of the bottom lid 103 are fittedinto the projections 102F formed at the rear right and left edges,symmetrically formed with respect to the width direction, on the uppersurface of the supporting plate 102. Accordingly, the bottom lid 103 ispositioned on the supporting plate 102. In the center of the projection102F is formed a threaded through-hole 102G, through which a screw 806is inserted. It should be noted that throughout the drawings, thevarious screws (including the screw 806 and various other screws) areexaggerated in scale to aid review of the drawings.

[0104] In the bottom lid 103 are formed four protrusions 103D projectingdownward in the height direction. A center portion of each protrusion103D is curved downward, i.e., having a lowest point in the lateralcenter, so that the protrusions 103D exhibit a curved plane (arcing fromleft to right) extending perpendicular to the longitudinal direction ofthe bottom lid 103. These four protrusions 103D press the upper surfaceof the extending portion 109B of the right slide plate 109 and theextending portion 110B of the left slide plate 110 (i.e., the rear twoprotrusions 103D press on the right side plate 109, while the front twoprotrusions 103D press on the left side plate 110) to create frictionforce when the right and left slide plates 109 and 110 are movedlaterally. This friction force gives a better operation feeling to theoptical barrels 300 and 400 slide laterally, as detailed below.

[0105] With the above constitution, the rack 109B2 of the right slideplate 109 and the rack 110B2 of the left slide plate 110 mesh with thepinion gear 105, so that the right slide plate 109 and left slide plate110 slide toward and away from each other in the lateral direction.Moreover, since the racks 109B2, 110B2 and the pinion gear 105 have thesame tooth pitch for engagement, the right slide plate 109 and leftslide plate 110 simultaneously move the same distance in the oppositedirection (with respect to each other).

[0106] A through-hole 103G is formed in an area surrounded by the rightand left protrusions 103B, at the front part of the bottom lid 103.

[0107] A user diopter adjustment mechanism is shown in FIGS. 6 through9, and portions thereof are shown in FIGS. 25A, 25B, 26A through 26C,and 27A through 27C. FIGS. 25A and 25B are perspective views of adiopter eccentric seat and diopter decorative ring, respectively. FIGS.26A, 26B, and 26C are orthogonal views of the diopter decorative ring ofFIG. 25B, showing top, side, and bottom views, respectively. FIGS. 27A,27B, and 27C are orthogonal views of the diopter eccentric seat of FIG.25A, showing top, side, and bottom views, respectively.

[0108] As shown in FIGS. 6 and 25B, the diopter decorative ring 106 hasa disc-shaped diopter correction body 106A having a disc diameter thatis larger than that of the through-hole 103G, a shaft portion 106Bprojected from the upper center of the body 106A, and a threaded hole106C that is formed on the shaft portion 106B, and having an axisparallel to that of the shaft portion 106B. As shown in FIGS. 6 and 25A,the diopter decorative ring 106 engages a diopter eccentric seat 107.The diopter is corrected by rotating the body 106A about the axis of theshaft portion 106B, as detailed below, which in turn rotates protrusions107C of the diopter eccentric seat 107 engaging indentations 106D, andthereby the entire diopter eccentric seat 107. As shown in FIG. 27B and27C, two engaging protrusions 107C are provided on opposite sides of theeccentric axis of the diopter eccentric seat 107, for engaging twoengaging slots 106D (shown in FIGS. 25B and 26A) of the diopterdecorative ring 106. Here, even if only one engaging slot 106D andcorresponding protrusions 107C of the diopter eccentric seat 107 engage,the mechanism can correct the diopter; that is, engagement via only oneengaging slot 106D and only one corresponding protrusion 107C may beconsidered equivalent, although engagement of two portions provides morepositive driving.

[0109] As shown in FIGS. 25A and 27A through 27C, the diopter eccentricseat 107 is provided with a disk-shaped body 107A having a disc diameterthat is larger than the inner diameter of the through-hole 103G, aneccentric hole 107B penetrating the disk-shaped body 107A in the heightdirection, with a predetermined eccentricity relative to a center of thebody 107A, and the two protrusions 107C which are inserted to the twoengaging slots 106D of the diopter decorative ring 106.

[0110] As assembled, the shaft portion 106B of the diopter decorativering 106 penetrates the through-hole 103G from the under side of thebottom lid 103, and is inserted into the eccentric hole 107B of thediopter eccentric seat 107. The two protrusions 107C of the dioptereccentric seat 107 are inserted into the two engaging slots 106D of thediopter decorative ring 106. As shown in FIGS. 6 through 8, a screw 805,having a spring washer 804, is inserted through the eccentric hole 107Bof the diopter eccentric seat 107 and affixed, so that the shaft portionof the screw 805 is screw coupled into the screw hole 106C formed at theshaft portion of the diopter decorative ring 106, fixing the dioptereccentric seat 107 on the diopter decorative ring 106 via the bottom lid103.

[0111] In such a constitution, as shown in FIG. 6, the body 106A of thediopter decorative ring 106 is exposed (downward from the bottom surfaceof the supporting plate 102) through the through-hole 102C. The diopterdecorative ring 106, coupled with the diopter eccentric seat 107, isdisposed at the center in the width direction of the binocular 1000 andnear to the front end of the binocular 1000.

[0112] Referring to FIGS. 6 and 24C, the periphery of the trough hole103G under the bottom lid 103 is formed with a protrusion 103J in theperipheral direction (hidden in FIG. 6, but shown in FIG. 24A). Theprotrusion 103J engages with a curved channel 106E on the upper portionof the diopter decorative ring 106 while engaged, so that the end of theperipheral curved channel 106E of the diopter decorative ring 106 abutsthe end of the peripheral protrusion 103J for controlling the amount ofthe rotation of the diopter decorative ring 106.

[0113] The diopter decorative ring 106 and the diopter correctioneccentric seat 107 are integrally fixed in the rotation direction of theshaft 106B, by the engagement between the concaved portion 106D and theprotrusions 107C, but are slightly movable in the shaft direction of theshaft portion 106B so as to permit detent “clicking” as described below.

[0114] Referring to FIGS. 6, 23, and 24A, an engagement portion 103Hcomposed of a plurality of detent knurled portions extends about theperipheral direction of the through-hole 103G, formed at the peripheralportion of the through-hole 103G of the upper surface of the bottom lid103. Further, a protrusion or set of protrusions 107D (hidden in FIG. 6,but shown in FIG. 27C) formed under the surface of the diopter eccentricseat 107 engages the engaging portion 103H. Although three protrusions107D are shown in FIG. 27C, one protrusion is sufficient (or two).Accordingly, the protrusion(s) 107D “clicks” with the engaging portion103H, while the diopter decorative ring 106 is rotated, giving acomfortable operational clicking feeling (tactile and/or auditoryfeedback) thereby. In this operation, the spring washer 804 presses theunder surface of the body 107A and the protrusions 107D of the dioptereccentric seat 107 onto the engaging portion 103H to provide sufficientplay to permit the “clicking” engagement without excessive tightness orjamming.

[0115] As shown in FIG. 9 and 10, the body 101 of the supporting unit100 is provided with a front wall 101A, a rear wall 101B, a right wall101C and a left wall 101D that connect the right and left side of thefront and rear wall 101A and 101B. The upper and under portions of thebody 101 are open to the top side in a rectangular shape.

[0116] The underside of the body 101, being covered by the bottom lid103, is coupled onto the supporting plate 102. Four screws 806 areinserted through four screw holes 102G formed on the supporting plate102, to be screw coupled to the four threaded holes 101E formed at theunder side of the body 101.

[0117] As shown in FIGS. 7 and 11, the upper plate 104 is formed in agenerally rectangular shape, is of approximately the same size as thesupporting plate 102, and covers the upper part of the body whenattached. Openings 104B and 104C are formed in the center in the widthdirection near to the rear end of the binocular, so that a portion ofeach of the focus arrangement ring 202 and zooming arrangement ring 204,respectively, which are accommodated therein, are exposed therethrough.

[0118] Rectangular shaped decorative plates 101I and face plate 101J arerespectively attached to the front side of the front wall 101A and therear side of the rear wall 101B.

[0119] In the supporting portion 100 mentioned above, the body 101,supporting plate 102, bottom lid 103 and the upper plate 104 areintegrally fixed. The right slide plate 109 and left slide plate 110 aresupported slidably in the width direction by the supporting plate 102.

[0120] The optical operating unit 200, shown in FIGS. 7, 10, and 11, isdescribed below.

[0121] Referring to both FIGS. 10 and 11, the optical operating unit 200is provided with a body 101 (FIG. 10), a main shaft 201 (FIGS. 10 and11), a focus arrangement ring 202 (FIGS. 10 and 11), a zoomingarrangement ring 204 (FIG. 11), a movement shaft 206 (FIGS. 10 and 11),a cam ring 207 (FIGS. 10 and 11), a first lens guiding piece 208 (FIGS.10 and 11), a second lens guiding piece 209 (FIG. 11), a cam frame 210(FIG. 11), a guiding piece shaft 211 and 212 (FIG. 11), a first lensslider 213 (FIG. 10), a second lens slider 214 (FIG. 10), a pressingplate 215 (FIG. 10), a cooperation shaft 216 (FIG. 10) and additionalparts as discussed below.

[0122] The main shaft 201 extends parallel to the optical axis of thelens barrels 300 and 400. The front and rear ends of the main shaft 201are supported respectively by axle bearings provided on the front wall101A and rear wall 101B of the body 101. The main shaft 201 rotatablysupports the focus arrangement ring 202 and the zooming arrangement ring204, as detailed below. The diopter decorative ring 106 is rotatablydisposed about an axis perpendicular to the axis of the main shaft 201.

[0123] On the outer peripheral surface of the front end portion, splines201A are formed extending along the axis direction, disposed at apredetermined distance about the periphery of the front end portion ofthe main shaft 201 and extending for a predetermined distance along thefront end portion of the main shaft 201. These splines 201A are insertedinto matching grooves 207B formed in a hole 207A of the cam ring 207.

[0124] The zooming arrangement ring 204 includes a ring-shaped body 204Aand a rubber ring 204B covering the outer periphery of the body 204A.

[0125] The body 204A includes a hole 204A1 having an inner bore throughwhich the rear portion of the main shaft 20l is inserted, the body 204Abeing coupled to the main shaft 201. A screw 808 screw-couples the body204A to the rear portion of the main shaft 201 from the rear side.

[0126] The cam ring 207, a cylindrically shaped cam with an outer wall,having a width in the peripheral direction and a length in the axisdirection, includes a hole 207A formed on the outer wall. The hole 207Ais provided with the grooves 207B formed along the diameter for engagingthe splines 201A of the main shaft 201. In such a manner, the cam ring207 is supported by the main shaft 201 to slide along the axis, but isnot rotatable around the main shaft 201. The outer peripheral surface207C of the cam ring 207 is provided with two first cam grooves 207D andtwo second cam grooves 207E formed about the outer peripheral surface207C.

[0127] As shown in FIGS. 10 and 11, the moving shaft 206 includes afirst shaft portion 206A provided at the rear portion thereof, a secondshaft portion 206B at the front portion thereof, a flange 206C formedbetween the first and second shaft portion, and a hole 206D penetratingthe first shaft portion 206A, the flange 206C and the second shaftportion 206B and extending along the axis of the moving shaft 206. Theinner diameter of the hole 206D is formed so that the main shaft 201 isrotatable while inserted therethrough.

[0128] A helical guiding groove 206A1 is formed on the outer peripheralsurface of the first shaft portion 206. The guiding groove 206A1includes a first groove portion 296A11 with a wide pitch along the shaftdirection, and a second groove portion 206A12 with a narrow pitch inthis order toward the object side.

[0129] The focus arrangement ring 202 includes a ring body 202A and arubber ring 202B, the rubber ring covering the circumference of the body202A. The diameters of the focus arrangement ring 202 and zoomingarrangement ring 204 are formed to be approximately the same size. Thatis, the outer diameters of the rubber ring 202B and 204B have nearly thesame size.

[0130] The inner peripheral surface 202A1 of the body 202A has two ballholders 202A11 formed therein on the opposite positions in the diameterdirection to hold two balls 203, in a manner such that the two balls 203can rotate but are not movable in the diameter direction.

[0131] An arm 202A1 is integrally formed on the body 202A (shown in FIG.11), extending in the diameter direction, to rotate when the focusarrangement ring is rotated. The balls 203 engaged in the engagementportion 202A11 on the arm 202A1, in such a case, move along the helicalguiding groove 206A1 formed in the first shaft portion 206A of themoving shaft 206. the helical guiding groove 206A1 is formed “doubledscrewed”, i.e., having a thread pitch that changes from coarser to fineralong its length, on the first shaft 206A of the moving shaft 206.

[0132] Protrusions 206C4, 206C5 (shown in FIG. 11) are formed on theright and left portion of the flange 206C of the moving shaft 206. Theprotrusions 206C4, 206C5 are arranged to engage and move along guidinggrooves 101C11 and 101D11 (shown in FIG. 9) formed extending along theright and left wall 101 c and 101D.

[0133] When assembled, each protrusion 206C1 and 206C2 abuts arespective bank 101C12 and 101D12 (shown in FIGS. 9 and 10) forrestricting the front range of the moving shaft 206. Moreover, eachprotrusion 206C4 and 206C5 abuts the rear wall 101G1 (shown in FIGS. 9and 10) of the body 101 for restricting the rear movable range.

[0134] As shown in FIG. 11, when the balls 203 engage the first groove206A11 (with a wide/coarser pitch), the moving amount of the movingshaft by rotation of the focus rotation ring 202 is larger than thatwhen engaging the second groove 206A12 (with a narrow/finer pitch).

[0135] The cam frame 210, shown in FIG. 11, has a front frame portion210A and three arms 210C1, 210C2, and 210D. The front frame portion 210Asubstantially has a shape of a ring of which top portion is taken away.The arms 210C1 and 210C2 extend parallel to the optical axis from theright and left top of the front frame portion 210A, respectively.Further, the arm 210D extends parallel to the optical axis from thebottom of the front frame portion 210A.

[0136] The front frame portion 210A also holds shafts 211 and 212beneath the arms 210C1 and 210C2, respectively, so that the shafts 211and 212 also extend parallel to the optical axis. The circumference ofeach shaft 211, 212 faces the center axis of the cam frame 210. Thefirst lens guiding piece 208 and the second lens guiding piece 209,respectively, are slidably held on shafts 211, 212.

[0137] The cam frame 210 is held by an inner surface of a right sidewall 101C and an inner surface of a left side wall 101D of the body 101,so that the cam frame 210 can move along the optical axis, but is notrotatable about the axis.

[0138] The main shaft 201 is inserted in a hole 207A of the cam ring207, the cam ring 207 axially and slidably supported by the main shaft201. The cam ring 207 is rotatably supported by the second shaft portion206B of the movement shaft 206 such that the cam ring 207 is rotatablerelative to, but fixed axially with respect to, the second shaft portion206B. A bayonet-type engagement formed on the second shaft portion 206Bnear the flange 206C and on the rear of the cam ring 207 is employed forthis purpose, although other structures would serve as well.Accordingly, the cam ring 207 is supported by the main shaft 201, andwith respect to the main shaft 201, is not rotatable but is movable inthe axial (optical axis) direction.

[0139] The cam frame 210, accommodating the cam ring 207, is coupled tothe flange 206C of the moving shaft 206 by three screws 809, so that thecam frame 210 and the moving shaft 206 are integrally fixed.

[0140] The rear portions of the right and left arms 210C1 and 210C2 arerespectively provided with threaded holes 210C11 and 210C21 openingrearward. In addition, a rear part of a connecting arm 210D facingrearward has a threaded hole formed therein (not shown), the threadedhole that is opening toward the rear of the binocular 1000. Threadedholes 210C11, 210C21 and the threaded hole opening to the rear are screwcoupled by screws 809 that are inserted through the through-holes 206C1,206C2 and 206C3 provided on the flange 206C of the moving shaft 206, sothat the cam frame 21 is fixed to the moving shaft 206. Moreover, therear end of the connecting arm 210D has a threaded hole 210D1 formedtherein facing downward.

[0141] The cam ring 207 has first cam grooves 207D and second camgrooves 207E formed therein.

[0142] As shown in FIGS. 10 and 11, the second lens guiding piece 209has two holding surfaces therein that are spherically concave so as tohold two balls 210B, the two balls 210B being rotatably engaged in thegrooves 207E of the cam ring 207. The first lens guiding piece 208 hastwo similar holding surfaces therein (hidden in FIGS. 10 and 11) thatare shaped spherically concave so as to hold another two balls 210B, theadditional two balls 201B being rotatably engaged in the grooves 207D ofthe cam ring 207.

[0143] When the cam ring 207, held by the cam frame 210, is rotated bythe rotation of the main shaft 201, the first and second cam grooves207D and 207E of the cam ring 207 rotate with respect to the cam frame210. This rotation movement makes the first and second lens guidingpieces 208 and 209 move along the axial direction. Here, the first andsecond lens guiding pieces are disposed at both sides of the cam frame210, facing each other and partially surrounding the cam ring 207, andmove in the opposite directions with respect to each other along theoptical axis by virtue of the engagement of the balls 210B and grooves207D, 207E. As noted, the grooves 207D overlap the grooves 207E in theoptical axis direction of the main shaft, which results in the movableranges of the first and second lens guiding pieces overlapping in theaxial direction of the main shaft 201.

[0144] The pressing plate 215 is a rectangular-shaped plate, providedwith a through-hole 215B in the height direction. A screw 810, insertedthrough the through-hole 215B, engages the bottom wall of the cam frame210 so that the pressing plate 215 is attached to the cam frame 210.That is, the pressing plate 215 moves, at least with respect to movementalong the optical axis, integrally with the moving shaft 206, the camring 207 and the cam frame 210 (although certain of these members arerotatable with respect to one another as set forth herein). The firstand second lens slide plates 213 and 214 are intermediate the pressingplate 215 and the bottom wall of the main body 101. Protrusions on theupper rear side of the pressing plate 215 maintain a clearance in whichthe slide plates 213 and 214 are movable in front and rear directions.

[0145] As shown in FIG. 10, the first lens slide plate 213 is screwcoupled to the first lens guiding piece 208 by a screw 811, and isintegrally movable with the first lens guiding piece 208. In a similarfashion, the second lens slide plate 214 is screw coupled to the secondlens guiding piece 209 (as shown in FIG. 11) by a screw 812, and isintegrally movable with the second lens guiding piece 209.

[0146] The first lens slide plate 213 is formed in one piece by a firstcenter portion 213A and a first arm 213B. The first center portion 213Ais a rectangular-shaped plate to be connected to the first lens guidingpiece 208, and the first arm 213B is first bent downward from the rightand left sides of the first center 213A and is then bent to extendhorizontally, laterally and linearly.

[0147] The first center portion 213A is provided with an engagementportion 213C for engaging the engaging portion 208A of the first lensguiding piece 208, the engagement portion 213C having a through-holethrough which the screw 811 is inserted and screw-couples the engagingportion 208A.

[0148] A guided portion 213E, 213F includes a protrusion extending alongthe axis at the area where the right and left first arm 213B connect tothe first center portion 213A. The right and left first arm portion 213Bextend laterally from the guided portions 213E, 213F. These guidedportions 213E, 213F are movably supported by the guiding portion 101C2and 101D2 of the body 101, movable along the optical axis direction.

[0149] The first center portion 213A is movably supported in the opticalaxis direction, with its upper and lower surfaces in the heightdirection being pressed respectively by the pressing plate 215 and bythe bottom of the body 101.

[0150] The right and left ends of the engaging arm 213B are provided,respectively, with channel grooves 213D formed extending laterallyoutward, the channel grooves 213D being engaged slidably with a firstlens unit 307 (shown in FIG. 14) and 407 (shown in FIG. 17) of the rightand left telescope optical system, the lens units 307 and 407 beingslidable in the lateral direction.

[0151] The second lens slide plate 214 is formed in one piece of asecond center portion 214A and two second arms 214B. The second centerportion 214A is a substantially rectangular-shaped plate to be connectedto the second lens guiding piece 209, and the second arm 214B is firstbent downward from the right and left sides of the second center plate213A and is then bent to extend horizontally, laterally and linearly.

[0152] The second center plate 214A is provided with an extensionextending toward the front of the binocular 1000, where an engagementportion 214C is formed for engaging the engaging portion 209A of thefirst lens guiding piece 209. The engagement portion 214C has athrough-hole through which the screw 811 is inserted and screw-couplesthe engaging portion 209A of the second lens guiding piece 209. The rearbottom surface of the extension 214A connects to and is substantiallyflush with the upper surface of the second center portion 214A.

[0153] A guided portion 214E, 214F includes a protrusion extendingparallel to the optical axis at the area where the right and left secondarms 214B connect to the second center portion 214A. The right and leftsecond arm portions 214B extend laterally from the guided portions 214E,214F.

[0154] These guided portions (214E, 214F) are movably supported by theguiding portion 101C2 and 101D2 of the body 101, movable along theoptical axis direction.

[0155] The second center portion 214A is movably supported in theoptical axis direction, with its upper and lower surfaces in the heightdirection being pressed respectively by the pressing plate 215 and bythe bottom of the body 101.

[0156] The right and left ends of the engaging arm 214B are providedrespectively with channel grooves 214D formed extending laterallyoutward, the channel grooves 214D being engaged slidably with a secondlens unit 308 (as shown in FIG. 14) and 408 (as shown in FIG. 17) of theright and left telescope optical system, slidable in the lateraldirection.

[0157] The first and second lens slide plates 213 and 214 are disposedin this order along the optical axis, and are intermediate the pressingplate 215 and the bottom of the body 101, wherein the upper surface ofthe first center portion 213A is abutted by the extension 214A1 of thesecond center portion 214A. With such a structure, the first and secondarms 213D and 214D are flush with each other, and the first and secondcenter portions 213A and 214A are nearly flush with each other.

[0158] Optionally, in order that the first and second lens sliders 213,214 take as little vertical space as possible, a longitudinal channel isformed in the upper surface of the first lens slider 213, which acceptseither the screw head of screw 812 (connecting the second lens slider214 to the second lens guiding piece 209), or the bottom of theextension 214A1 of the second lens plate 214 (also including the screwhead of the screw 812). In such a case, the longitudinal channel permitsthe accepted portion to move in the longitudinal optical axis directionwithout interfering with the first lens slider 213.

[0159] A hole 215A, penetrating the pressing plate 215 laterally (leftto right), is formed on the pressing plate 215 on its front area, and asliding shaft 216 is inserted into the hole 215A and supported by thepressing plate 215, extending outward toward the right and left side ofthe shaft 216.

[0160] The right and left moving units 303 (as shown in FIG. 13) and 403(as shown in FIG. 16), supporting the right and left eyepiece opticalsystem, are respectively provided with engaging portions 303A1 and 403A1that engage with the moving shaft 216 so that the right and left movingunit 303 and 403 are supported slidably to slide not only in the lateraldirection along the moving shaft 216 but also to slide in the opticalaxis direction together integrally with the moving shaft 216.

[0161] The body 101 of the supporting unit 100 includes a firstcontainer 101G and a second container 101H, disposed along the opticalaxis with a space therebetween along the optical axis. The firstcontainer 101G accommodates the focus arrangement ring 202, held in amanner to be rotatable about the axis but unmovable along the axisdirection. The second container 101H accommodates the zooming ring 204,also rotatable but unmovable along the axis direction.

[0162] In the structure mentioned above, when the zooming arrangementring 204 is rotated without rotating the focus arrangement ring 202, themain shaft 201 fixed to the zooming arrangement ring 204 is rotated, sothat the cam ring 207 fixed to the front end of the main shaft 201 isaccordingly rotated in the inside of the cam frame 210.

[0163] Accordingly, the first and second cam grooves 207D and 207E,provided on the peripheral outer surface of the cam ring 207, rotatewith respect to the cam frame 210. The first and second lens guidingpieces 208 and 209, engaging with the balls 210B, cooperating with therotation of the first and second cam grooves 207D and 207E, and guidedby the guiding shafts 211 and 212, are moved along the axial direction.As mentioned above, the first and second lens guiding pieces 208 and 209move in reverse (opposite) directions with respect to each other whenthe zooming arrangement ring 204 is rotated.

[0164] In case the focus arrangement ring 202 is rotated withoutrotating the zooming arrangement ring 204, the shaft 201 is not rotated.Consequently, the balls 203, engaging the body 202A of the focusarrangement 202, are not moved along the axis direction but rotate aboutthe axis while engaging in the guiding grooves 206A1 of the moving shaft206. Accordingly, the moving shaft 206 and the cam frame 210, integrallyfixed to the shaft 206, are moved inside of the body 101, along the axisof the main shaft.

[0165] As mentioned above, the guiding grooves 206A include a firstgroove 206A11 with a long/wide (coarse) pitch, and a second groove206A12 with a short/narrow (fine) pitch, the first and second groove206A11 and 205A12 being connected with each other.

[0166] Accordingly, when the moving shaft 206 and the cam frame 210 movealong the optical axis with the balls 203 engaged in the first groove206A11, the amount of movement is much more than that with the balls 203in the second groove 206A12. Therefore, the lens barrels can be promptlydrawn into the body in the former case (first groove 206A11), and thefocal distance can be precisely arranged in the latter case (secondgroove 206A12).

[0167] The right lens barrel 300 and left lens barrel 400 are describedbelow with reference to FIG. 5.

[0168] The left and right assemblies have numerous similarities. Forexample, the right lens barrel 300 and left lens barrel 400 include aplurality of laterally symmetric elements with the same functions.Accordingly, the present description, where elements are laterallysymmetric, is restricted to the right side, and the explanation for theleft side is omitted. One skilled in the art will recognize how thedescription for the right side may be related to the correspondingelements on the left side. A consistent numbering scheme is usedthroughout this specification, such that when a part is described forthe right lens barrel in the “300” series, a corresponding part on theleft lens barrel is numbered similarly in the “400” series. Accordingly,the description with respect to the right side “300” series should beconsidered to apply to those numbered elements of the left side “400”series that appear in the drawings, but that have not been specificallydescribed herein by such numbers. Of course, where those numberedelements of the left side “400” have been specifically described, thedescription thereof should be considered. Those elements laterallycorresponding to each other are designated with the same combination ofnumbers and alphabetical designations.

[0169] As shown in FIG. 5, the right lens barrel 300 includes a rightframe 301, a right frame lid 302, a right movement unit 303, a righteyepiece cylinder 304, a right objective unit 305, a right prism unit306, a first lens unit 307, a second lens unit 308, a right eyepieceunit 309, a right outer unit 310 and other parts as described below.

[0170] The right frame lid 302, the right objective unit 305 and theright outer unit 310, being attached to the right frame 301, are mountedto the right slide plate 109 (refer to FIG. 7), movable in the lateraldirection together with the slide plate 109.

[0171] As shown in FIGS. 5 and 13, the right moving unit 303 is slidablewith respect to the right frame 301 along the optical axis. The rightprism unit 306 is provided at the front portion of the right moving unit303. A right eyepiece cylinder 304 is coupled to the rear portion of theright moving unit 303. The eyepiece cylinder 304 (shown in FIGS. 5 and14) includes an eyepiece unit 309 that is coupled to the rear portion ofthe right eyepiece cylinder 304. Moreover, as shown in FIGS. 5 and 14, afirst lens unit 307 and a second lens unit 308 are slidably disposedbetween the right moving unit 303 and the right eyepiece cylinder 304.

[0172] That is, the objective unit 305 is mounted to the right frame301, while the prism unit 306, the first lens unit 307, the second lensunit 308 and the eyepiece unit 309 are mounted to the right moving unit303. Therefore, the right moving unit 303 moves slidably with respect tothe right frame 301 along the optical axis, so that as the distancebetween the objective unit 305 and the right prism unit 306, the firstlens unit 307, the second lens unit 308 and the eyepiece unit 309changes, accordingly, the focal distance is arranged.

[0173] Next, referring to the FIGS. 8 and 12 to 14, the structure of theright lens barrel will be detailed.

[0174] As shown in FIG. 12, right frame 301 is provided with a holdingmember 301B for holding the rear part of a right guiding shaft 301A (atthe center in the height direction of the rear right side). The underpart of the holding member 301B has a threaded hole 301C formedtherethrough, to which a screw is engaged for mounting the right frame301 to the right slide plate 109 (refer to the arrow “B”).

[0175] Referring to FIG. 8, the attachment of the right frame 301 to theright slide plate 109 is described below in detail.

[0176] Screws 820, 820 (front and rear) are screw coupled to a screwhole formed on the rear part of the right frame 301 (not shown) and to ascrew hole (not shown) formed on a frame lid 302 (shown in FIG. 12, anddiscussed below), via guiding grooves 102H1 and 102H2 of the supportingplate 102 and through-holes 109C1 and 109C2. In such a structure, thehead of the screws 820 and 820 are accommodated in the guiding grooves102H1 and 102H2 on the supporting plate 102 without interfering thereto,thereby being laterally slidable.

[0177] Screw 821, 821 are screw coupled to screw holes formed on thefront and rear area of the right frame 301 via through-holes 109D1 and109D2 (the front screw hole corresponds to the screw hole 301C; refer toarrow “B” in FIGS. 8 and 12). Here, the heads of the screw hole 821 and821 can be moved to and accommodated into notches 102J1 and 102J2 in theouter lateral side at front and rear of the supporting plate 102,without interfering thereto, thereby being laterally movable.

[0178] In such a structure, the right frame 301 is mounted on the rightslide plate 109 by means of the screws 820 and 821.

[0179] The left frame 401 (shown in FIG. 15) is also similarly mountedto the left slide plate 110 as described immediately below.

[0180] As shown in FIG. 8, screws 822, 822 are screw coupled to thescrew hole (not shown) formed on the rear part of the left frame 401 andto the screw hole (not shown) formed on the frame lid 402 (discussedbelow), via guiding grooves 102I1 and 102I2 of the supporting plate 102and through-hole 110C1 and 110C2. In such a structure, the head of thescrews 822 and 822 are accommodated in the guiding groove 102I1 and102I2 on the supporting plate 102I1 without interfering therewith,thereby being laterally slidable.

[0181] Screw 823, 823 are screw coupled to screw holes formed on thefront and rear area of the left frame 401 via through-holes 110D1 and110D2. Here, the heads of the screw hole 823 and 823 can be moved to andaccommodated into the notches 102K1 and 102K2, without interferingtherewith, thereby being laterally movable.

[0182] In such a structure, the left frame 401 is mounted on the leftslide plate 110 by means of the screws 822 and 823.

[0183] Returning to the right lens barrel 300, as shown in FIG. 12, theright frame 301 is provided with a supporting member 301E at theapproximately center area in the height direction of the left rearportion of the right frame 301, for supporting the rear portion of theleft guiding shaft 301D (refer to arrow A).

[0184] The right frame 301 is provided with a threaded hole 301F formedapproximately in the center area in the height direction of the frontright wall, to which a screw 813 is screw coupled. The guiding shaft301A is intermediate the head of the screw 813 and the right wall forsupporting the guiding shaft.

[0185] As shown in FIG. 12, the right frame 301 has a threaded hole 301Gformed at the right upper portion of its front wall. A screw 814 isscrew coupled to the screw hole 301G via a through-hole 302A, so thatthe right frame lid 302 is fixed to the front of the right frame 301.Further, the front end of the guiding shaft 301D (shown in FIG. 13) issupported by the right frame lid 302.

[0186] Moreover, a screw hole 302B is formed at the front portion of theright frame lid 302, to which a screw 815 is coupled via through-hole310A22 that is provided on the front wall 310A2 of the right outerhousing 310A. Accordingly, the front portion of the right frame 301 isfixed to the front wall 310A2 of the outer housing 310A.

[0187] A screw 816 is screw coupled to an upper portion of the screwhole 301F of the right frame 301 via through-hole 310A41 that is formedon the right wall 310A4 of the right outer housing 310A. Accordingly,the right side of the right frame 301 is fixed to the right wall 310A4of the right outer housing 310A.

[0188] A screw hole 301H is formed on the rear left side of wall of theright frame 301, to which a screw 817 is screw coupled via through-hole310A32 that is formed on the rear wall 310A3 of the right outer housing310A. Accordingly, the rear side of the right frame 301 is fixed to therear wall 310A3 of the right outer housing 310A.

[0189] A hole 301J is formed on the rear left portion of the rear wall,opening rearward, to which an insertion projection 310C2 of the rightrear cover 310C (discussed below) is inserted.

[0190] The right outer housing 310 includes a right outer housing 310A,a right front cover 310B, a right rear cover 310C and other parts asdescribed herein.

[0191] As shown in FIG. 12, a right outer housing 310A includes a bottomwall 310A1, and a front wall 310A2, rear wall 310A3 and right side wall310A4 that extend from, respectively, the front, rear and right edge ofthe bottom wall 310A1.

[0192] An opening 310A21 is formed on the front wall 310A2 for theobjective optical system, and an opening 310A31 is formed in the rearwall 310A3 for the right eyepiece cylinder 304, including a third lens309C, to move therethrough.

[0193] A “V” shaped notch 310A51 is formed on the left edge and rearside of the upper wall 310A5 for accommodating the focus arrangementring 202 and the zooming arrangement ring 204.

[0194] The right front cover 310B is attached to the front side of thefront wall 310A2 via a double sided adhesive tape 310D, with the opening310B1 aligned with the opening 310B1.

[0195] The right rear cover 310C is attached to the rear side of therear wall 310A3 via a double sided adhesive tape 310E, with the opening310C1 aligned with the opening 310A31.

[0196] As shown in FIG. 5 and 12, the rear wall 310A3 of the right outerhousing 310A is provided with a through-hole 310A33, corresponding tothe hole 301J of the right frame 301, through which the insertionprojection 310C2 of the right rear cover 310C is inserted into the hole301J, so that the right rear cover 310C is positioned with respect tothe right frame 310 and the right outer housing 310A.

[0197] A half-circular notch 310A11 is formed on the front left edge onthe bottom wall 310A1 of the right outer housing 310A. The half-circularnotch is formed in such a manner to avoid, i.e., not to interfere with,the diopter decorative ring 106.

[0198] As shown in FIG. 13, the objective unit 305 includes an objectiveframe 305A, an objective pressing ring 305B, an objective lens 305C andother parts as described below.

[0199] The objective frame 305A includes a cylindrical body 305A1, afirst holding portion 305A2 provided on the right side of the body305A1, a second holding portion 305A3 extending rearward from the leftside of the body 305A1, and an engaging portion 305A4 extending to theleft from the front area of the second holding portion 305A3.

[0200] The inner circumference of the body 305A1 is female threaded, andan outer circumference of the pressure ring 305B is male threaded. Theobjective lens 305C is intermediate the body 305A1 and the pressure ring305B, fixing the objective lens 305C securely therebetween.

[0201] The first holding portion 305A2 is provided slidably along theguiding shaft 301A (shown in FIG. 12), holding the guiding shaft 301A.

[0202] As shown in FIG. 13, the second holding portion 305A3 is providedwith a spindle hole 305A31, parallel to the optical axis, through whichthe guiding shaft 301D is slidably held. Thus, the objective frame 305Ais configured to be slidable along the guiding shafts 301A and 301D.

[0203] Therefore, the objective lens 305C, being fit in the objectiveframe 305A, can be positioned anywhere along the range of positionsdefined by the guiding shafts 301A and 301D, along their axes.

[0204] The engaging portion 305A4 is formed in a substantiallyrectangular shape, having two engaging walls 305A41 extending downwardat the front and rear edges thereof. The two engaging walls 305A41 areparallel to one another, extending in the lateral (left to right)direction.

[0205] The outer circumference surface of the diopter eccentric seat 107is intermediate, i.e., held between the two engaging walls 305A41, andwhen the diopter eccentric seat 107 is rotated, the outercircumferential surface of the diopter eccentric seat 107 iseccentrically rotated, moving the two engaging walls 305A41 abuttedthereto along the optical axis direction.

[0206]FIG. 18, 19 and 20 respectively show a bottom plan view of thebinocular, in which the indicia zero point “0” mark 106F, plus “+” mark106G and minus “−” mark 106H of the diopter decorative ring 106 arerespectively aligned with the reference mark 102L.

[0207]FIGS. 5, 6 and 18 show that when the diopter eccentric seat 107 isrotated, the right objective frame 305A is moved along the optical axis,guided by the guiding shafts 301A, 301D, thereby arranging the locationof the objective lens 305C along the optical axis.

[0208] That is, the right objective frame 305A is moved with respect tothe right frame 301 by the rotation of the diopter eccentric seat 107(engaged with the engaging walls 305A41) about the shaft portion 106 ofthe diopter decorative ring 106.

[0209] As shown in FIG. 4, when the diopter decorative ring 106 isarranged so that the zero point “0” mark 106F is aligned with thereference mark 102 provided on the supporting plate 102, the rightobjective frame 305A is arranged to be situated at the center point inthe adjustable range with respect to the right frame 301. As previouslydescribed, the diopter decorative ring 106 and the diopter eccentricseat 107 are rotatably supported by the bottom lid 103 that is fixed onthe supporting plate 102.

[0210] That is, when the diopter eccentric seat 107 is rotated, theright objective frame 305A is moved along the guiding shafts 301A and301D (i. e., in the optical direction).

[0211] As shown in FIG. 13, the right moving unit includes a bottom wall303A that is rectangularly shaped, a rear wall 303B extends from therear edge of the bottom wall 303A, and a side wall 303C extends from theleft edge of the bottom wall 303A.

[0212] An engaging portion 303A1 is formed, extending laterally, on theleft edge at approximately the center thereof in the optical axisdirection. The engaging portion 303A1 engages the moving shaft 216(shown in FIG. 9) slidably, i.e., in a manner that is slidable along theshaft in the shaft direction.

[0213] The rear wall 303B is provided with a circular hole 303B1 in thecenter of the rear wall 303B. The bottom wall 303A is provided with abearing 303D at the right edge of the bottom wall 303A, for receivingthe guiding shaft 301A (shown in FIG. 12). The side wall 303C isprovided with a bearing 303E at the lower part of the side wall 303C,for receiving the guiding shaft 301D (shown in FIG. 13).

[0214] Therefore, the right moving unit 303 is movably supported by thebearings 303D and 303E, being guided respectively by guiding shafts 301Aand 301D along the optical axis.

[0215] As shown in FIG. 13, a prism unit 306 includes a holder 306A, anintermediating plate 306B, a holder lid 306C, a thin plate 306D, a firstprism 306E, a second prism (Dach or roof prism) 306F and so on.

[0216] The holder 306A includes an upper and bottom wall 306A1 and 306A2supporting the upper and bottom surfaces of the first prism 306E andsecond prism 306F, and a rectangularly shaped rear wall 306A3 connectingthe rear edges of the upper wall 306A1 and bottom wall 306A2.

[0217] The first prism 306E and the second prism 306F, constituting anerecting prism, are disposed in this order from the objective side,arranged to pass light and erect and image passing therethrough. Theintermediate plate 306B is disposed between an outcoming plane of thefirst prism 306E and an incident plane of the second prism 306F, so thatthe first and second prism 306E and 306F are securely attached to anupper wall 306A1 and a bottom wall 306A2 of the holder 306A (e.g., viaan adhesive).

[0218] A holder lid 306C includes a front wall 306C1, and a right andleft side wall 306C2 and 306C3 extending toward the rear from the rightand left edges of the front wall, for connecting the edges of the upperwall 306A1 and the bottom wall 306A2 of the holder 306A1. The front wall306C1, opposing the incident surface of the first prism 306E, has anopening 306C11 formed therethrough, through which light passes.

[0219] The rear wall 306A3 of the holder 306A is also provided with anopening, through which the outcoming light from the second prism 306Fpasses.

[0220] The thin plate 306D is disposed between the rear side of the rearwall 306A3 of the holder 306A and the rear wall 303B of the moving unit303. In the center of the thin plate 306D, an opening 306D1 is formedfor passing light.

[0221] The rear wall 306A3 of the holder 306A is provided with twothreaded holes 306A31 formed therein, opposing each other across theopening of the hole. Two screws 815 are screw coupled to the twothreaded holes 306A31 of the rear wall 306A3 of the holder 306A, viaspring (or lock) washer 816, washer 817, the through-hole 303B2 of therear wall 303B of the moving unit 303, and the through-holes 306D2 ofthe thin plate 306D, so that the holder 306A is integrally fixed to themoving unit 303.

[0222] The rear wall 303B of the moving unit 303 has protrusions 303B3,which extend rearward and in which are formed threaded holes 303B31 inthe height direction therethrough.

[0223] As shown in FIG. 14, the right eyepiece cylinder 304 includes abottom wall 304A and an upper wall 304E, as well as a right side wall304B, a left side wall 304C and a rear wall 304D that extend,respectively from the right edge, left edge and the rear edge of thebottom wall 304A. The upper wall 304E is connected to the upper edges ofthe right side wall 304B, the left side wall 304C and the rear wall304Dd.

[0224] The front edges of the bottom wall 304A, the right wall 304B andthe upper wall 304E are formed to receive the rear wall 303B of themoving unit 303 (shown in FIG. 13), and are provided with respectivescrew holes 304F. Three screws 818 are screw coupled to the threadedholes 303B31 (shown in FIG. 13) formed on the corresponding protrusions303B3 of the rear wall 303B through respective through-holes 304F, sothat the rear wall 303B is securely coupled to the right eyepiececylinder 304.

[0225] Therefore, the right eyepiece cylinder 304, the prism unit 306and the moving unit 303 are integrally coupled so as to be movable withrespect to the right frame 301 and the objective unit 305, guided by theguiding shaft 301A and 301D along the optical axis.

[0226] As shown in FIG. 14, first and second guiding shafts 311, 312 areprovided, parallel with each other along the optical axis, between therear surface of the rear wall 303B of the moving unit 303 (shown in FIG.13) and the front surface of the rear wall 304D of the right eyepiececylinder 304 (shown in FIG. 13).

[0227] As shown in FIG. 14, the first lens unit 307 includes a firstlens frame 307A and a first lens 307B.

[0228] As shown in FIGS. 28 through 32, the first lens frame 307Aincludes a body 307A1, a first front shaft bearing 307A3, a first rearshaft bearing 307A5 and a first extension 307A4 that are provided at theright edge of the body 307A1, and a second shaft bearing 307A6 providedat the left edge of the body 307A1.

[0229] The body 307A1 includes a first ring shaped portion 307A11 and asecond ring shaped portion 307A12. The second ring shaped portion 307A12is provided in front of the first ring shaped portion 307A11 coaxially.

[0230] The first ring portion 307A11 is provided with three springmembers 307A13 at its inner circumference, which are disposed in thecircumferential direction at regular intervals. The first lens 307B isdisposed between the spring members 307A13 and the second ring shapedportion 307A12. The spring members 307A13 bias the first lens towardsthe second ring shaped portion 307A12 to keep it from dropping out fromthe first lens frame 307A.

[0231] An engaging arm 307A2 extends forward from the lower part of thebody 307A1. An engaging protrusion 307A21 is formed at the bottom of thefront end of the engaging arm 307A2. The engaging protrusion 307A21engages with the groove 213D, which is provided on the right arm 213B ofthe first lens slide plate 213, movable in the direction perpendicularto the optical axis but immovable in the direction parallel to theoptical axis. Therefore, the first lens frame 307A, and first lens 307Bheld in it, move integrally with the first lens slide plate 213 in theoptical axis direction.

[0232] The first front shaft bearing 307A3 is provided at the outerright edge of the first ring shaped portion 307A11 of the body 307A1.The first extension 307A4 extends rearward, and parallel to the opticalaxis, from the first front shaft bearing 307A3. The first rear shaftbearing 307A5 is provided at the rear end of the first extension 307A4.Thus, the first rear shaft bearing 307A5 is disposed a predetermineddistance apart from the first front shaft bearing 307A3 in the opticalaxis direction.

[0233] The first front shaft bearing 307A3 and the first rear shaftbearing 307A5 are each provided with a hole 307A31 and 307A51,respectively, into which the first guiding shaft 311 is to be inserted.The holes 307A31 and 307A51 are provided so that their central axes areparallel to the optical axis and aligned with each other. The holes307A31 and 307A51 are formed so that they engage with the first guidingshaft 311 slidably along the optical axis direction without play withinthe plane perpendicular to the optical axis. In the present embodiment,the holes 307A31 and 307A51 are formed to have a circular cross sectionof a diameter substantially the same as that of the first guiding shaft311.

[0234] The first extension 307A4 has an abutting portion 307A43 at itsinside to which a fourth shaft bearing 308A6, described below, abutsfrom the direction perpendicular to the first shaft 311. As shown inFIG. 29, the abutting portion 307A43 has a L-shape, including two walls307A41 and 307A42. The wall 307A41 extends laterally and faces downwardtoward the first guiding shaft 311, and the wall 307A42 extendsvertically or perpendicular to the wall 307A41 and faces toward thefirst lens 307B.

[0235] As is shown in FIG. 30, an arm 307A62 extends rearward in theoptical axis direction from the outer left edge of the first ring shapedportion 307A11. The second shaft bearing 307A6 is provided at the rearend of the arm 307A62.

[0236] The second shaft bearing 307A6 is provided with a hole 307A61into which the second guiding shaft 312 is to be inserted. In thepresent embodiment, the second shaft bearing 307A6 and its hole 307A61are arranged so that the second shaft bearing 307A6 engages with thesecond guiding shaft 312 that is disposed on a plane defined by thefirst guiding shaft 311 and the optical axis. The hole 307A61 is formedas a rectangular shaped hole in cross section whose longitudinaldirection is substantially perpendicular to the optical axis direction.

[0237] As shown in FIG. 14, the second lens unit includes a second lensframe 308A, a second lens pressing ring 308B and a second lens 308C. Thesecond lens frame 308A includes, as shown in FIG. 33 through 37, a body308A1 that includes a cylindrical wall 308A11 and a front wall 308A12.The front wall 308A12 is formed on the front edge of the cylindricalwall 308A11 and has a rectangular-shaped opening 308A13.

[0238] The inner circumference of the cylindrical wall 308A11 is formedso as to hold the outer circumference of the second lens 308C. A femalescrew is provided to the inner circumference of the cylindrical wall308A11 so that the pressing ring 308B (shown in FIG. 14), which isprovided with a male screw on the outer circumference, can be screwed into hold the second lens 308C between the cylindrical wall 308 A11 andthe pressing ring 308B.

[0239] The second lens frame 308A further includes an engaging arm 308A2extending forward from the lower edge of the body 308A1. The lower frontend of the engaging arm 308A2 includes an engaging protrusion 308A21formed thereon for engaging the channel groove 214D (shown in FIG. 9)provided on the left arm 214B of the second lens slide plate 214. Theengaging protrusion 308A21 is engaged with the channel groove 214D so asto be movable laterally, but immovable in the optical axis direction.Therefore, the lens frame 308A, and the second lens 308C held therein,moves with the second lens slide plate 214 integrally in the opticalaxis direction.

[0240] A third rear shaft bearing 308A5 is provided on the outer leftedge of the cylindrical wall 308A11 of the body 307A1. A secondextension 308A4 is also provided on the outer edge which extends forwardfrom the third rear shaft bearing 308A5 parallel to the optical axis.Further, a third front shaft bearing 308A3 is provided at the front endof the second extension 308A3. Thus, the third front shaft bearing 308A3is disposed spaced apart form the third rear shaft bearing 308A5 in theoptical axis direction.

[0241] The third front shaft bearing 308A3 and the third rear shaftbearing 308A5 are each provided with a hole 308A31 and 308A51,respectively, into which the second guiding shaft 312 is to be inserted.The holes 308A31 and 308A51 are provided so that their central axes areparallel to the optical axis and aligned with each other. The holes308A31 and 308A51 are formed so that they engage with the second guidingshaft 312 slidably along the optical axis direction without play withinthe plane perpendicular to the optical axis. In the present embodiment,the holes 308A31 and 308A51 are formed in a circular-shape of a diametersubstantially the same as that of the second guiding shaft 312.

[0242] The inside wall of the second extension 308A4 is an abuttingportion 308A43 to which a second shaft bearing 307A6 abuts from thedirection perpendicular to the second shaft 312. As shown in FIG. 37,the abutting portion 308A43 of the present invention is L-shaped andextending parallel to the optical axis. The abutting portion includeswalls 308A41 and 308A42. The wall 307A41 extends laterally and facesupward toward the second guiding shaft 311, and the wall 307A42 extendsvertically or perpendicular to the wall 307A41 and faces toward thesecond lens 407C.

[0243] The second lens frame 308A is further provided with a fourthshaft bearing 308A6 at the right edge of the cylindrical wall 308A11.The fourth shaft bearing 308A6 is provided with a hole 308A61 into whichthe second guiding shaft 312 is to be inserted. The hole 307A61 isformed as rectangular shaped hole whose longitudinal direction issubstantially perpendicular to the optical axis direction.

[0244] As shown in FIG. 14, the eyepiece unit 309 includes an eyepiecelens frame 309A, an eyepiece lens pressing ring 309B, an eyepiece lens(third lens) 309C and an eyepiece 309D.

[0245] The inner circumferential surface of the eyepiece lens frame 309Ais formed to hold the outer circumferential edge of the third lens 309C.The female thread 309A1, formed around the inner circumference, isscrewed by the male thread 309B1 of the outer circumferential edge ofthe pressing ring 309B, so that the third lens 309C is held between theeyepiece lens frame 309A and the eyepiece lens pressing ring 309B.

[0246] The rear wall 304D of the right eyepiece cylinder 304 has athrough-hole formed therein in the length (front to back) direction ofthe rear wall 304D,through which hole's inner circumference is provideda female thread for providing an attaching portion 304D1. A femalethread of the attaching portion 304D1 is screwed by the male thread309A2 formed around the outer circumference of the eyepiece lens frame309A, so that the eyepiece lens frame 309A is fixed to the attachingportion 304D1.

[0247] The upper surface of the bottom wall 304A of the right eyepiececylinder is provided with a receiving groove 304A1 extending along theoptical axis direction, for receiving the rear portion of the engagingarm 307A2 of the first lens frame 307A while permitting movement alongthe optical axis direction. Additionally, a receiving groove 304A2 isformed on the surface of the upper surface of the bottom wall 304A,extending parallel to and separated by a predetermined distance from thereceiving groove 304A1 mentioned above, for receiving and guiding therear portion of the engaging arm 308A2 of the second lens frame 308Aalong the optical axis direction.

[0248] As shown in FIG. 19, the front portion of the engaging arm 307A2of the first lens frame 307A and the front portion of the engaging arm308A2 of the second lens frame 308A extend from the front edge of thebottom wall 304Aa of the right eyepiece cylinder 304.

[0249] The under surface of the bottom wall 303A of the moving unit 303is provided with guiding grooves 303A2 and 303A3 extending along theoptical axis direction. The guiding groove 303A2 guides the frontportion of the engaging arm 307A2 of the first lens frame 307A, and theguiding groove 303A3 guides the front portion of the engaging arm 308A2of the second lens frame 308A.

[0250] The engaging arms 307A2 and 308A2 are movably supported by themoving unit 303 and the right eyepiece cylinder 304, to move along theoptical axis.

[0251] Referring to the FIGS. 38 through 41, it will now be describedhow the first and second lens frames are assembled.

[0252] The first and second guiding shafts 311 and 312 are disposed atboth side of the first and second lens frame 307A and 308A, parallel tothe optical axis. Preferably, the first and second guiding shafts 311and 312 are arranged such that the optical axis and the first and secondguiding shafts 311, 312 are on a same plane.

[0253] The body 307A1 of the first lens frame 307A is disposed in frontof the body 308A1 of the second lens frame 308A such that the secondshaft bearing 307A6 of the first lens frame 307A is located between thethird front and rear shaft bearing 308A3, 308A5 of the second lens frame308A, and the fourth shaft bearing 308A6 of the second lens frame 308Ais located between the first front and rear shaft bearing 307A3, 307A5of the first lens frame 307A.

[0254] In this condition, the arm 307A62 of the first lens frame 307Aabuts against the abutting portion 308A43 of the second lens frame 308Aat its outer side 307A63. Thus, the arm 307A62, and as a result thesecond shaft bearing 307A6, are positioned at a location where the hole307A61 of the second shaft bearing 307A6 is substantially aligned withthe holes 308A31 and 308A51 provided to the third front and rear shaftbearing 308A3 and 308A5.

[0255] Further, the fourth shaft bearing 308A6 also abuts against theabutting portion 307A43 of the first lens frame 307A at its outer side308A62. As a result, the hole 308A61 formed in the fourth shaft bearing308A6 is positioned at a location where it is substantially aligned withthe holes 307A31 and 307A51 formed in the first front and rear shaftbearing 307A3 and 307A5.

[0256] Then the first guiding shaft 311 is inserted into the holes307A31, 308A61, and 307A51 to engage slidably with the first front shaftbearing 307A3, the fourth shaft bearing 308A6, and the first rear shaftbearing 307A5. The first guiding shaft 311 is inserted into the holes307A31, 308A61, and 307A51 readily since these three holes are alignedalong a straight line in the manner described above. The second guidingshaft 312 is readily inserted into the holes 308A31, 307A61, and 308A51,in a manner similar to the first guiding shaft 311, to engage slidablywith the third front shaft bearing 308A3, the second shaft bearing307A6, and the third rear shaft bearing 308A5.

[0257] By the constitution mentioned above, the first lens frame 307A iscoupled to the first guiding shaft 311 at two locations, namely at thefirst front shaft bearing 307A3 and at the first rear shaft bearing307A5, that are spaced apart along the first guiding shaft 311.Therefore, the first lens frame 307A slides along the first guidingshaft 311 without play within a plane perpendicular to the first guidingshaft 311 or the optical axis. Further, the first lens frame does notrotate about the first guiding shaft 311 since it is also coupled to thesecond guiding shaft 312 by the second shaft bearing 307A6.

[0258] Similarly (although not identically), the second lens frame 308also engages with the second guiding shaft 312 without play due to thethird front and rear shaft bearings 308A3 and 308A5, and is kept fromrotating about the second guiding shaft 312 by the engagement betweenthe fourth shaft bearing 308A6 and the first guiding shaft 311.

[0259] Accordingly, the first and second lens frames 307A and 308A movesthe first lens 307B and the second lens 308C, respectively, along theoptical axis precisely without play.

[0260] Moreover, the space occupied with the shaft bearings (307A3,307A5, 307A6, 308A3, 308A5, and 308A6) is reduced in the optical axisdirection since the second shaft bearing 307A6 is located between thethird front and rear shaft bearing 308A3 and 308A5, and the fourth shaftbearing 308A6 is located between the first front and rear shaft bearing307A3 and 307A5. This results in minimizing the whole size of a lensmoving mechanism including the first and second lens frame 307A, 308A.

[0261] The magnifying power of the telescope optical system is varied bymoving the first lens frame 307A and the second lens frame 308A toapproach to/move away form each other. Here, the telescope opticalsystem includes the objective lens 305C, the prism unit 306, the firstlens 307B, the second lens 308C and the third lens 309C.

[0262] That is, in this telescope system, the objective lens systemincludes the objective lens 305C, and the eyepiece lens system includesthe first lens 307B, the second lens 308C and the third lens 309C.Moving the first lens 307B to approach to/move away from the second lens308C in the optical direction varies the magnifying-power of thetelescope system.

[0263] The left side first and second lens frames 407A and 408A aresubstantially similar to the right side lens frames 307A and 308A.Accordingly, the description above with respect to the right side lensframes 307A and 308A and associated parts and interaction should beconsidered to apply to the left side lens frames 407A and 408A. As notedabove, the left and right assemblies have numerous similarities, and inthe following description, the description with respect to the rightside “300” series should be considered to apply to those numberedelements of the left side “400” series that appear in the drawings, butthat have not been specifically described herein by such numbers.

[0264] Of course, where those numbered elements of the left side “400”series are specifically described, the elements differ from those of theright side, and the description thereof should be considered.Hereinbelow, the left frame 401 and the left objective frame 405 (of theelements in the left lens barrel 400), which are constituted differentlyfrom those of the right lens barrel 300, are described.

[0265] As shown in FIG. 15, the left frame 401 is provided with a holder401B formed on the rear left portion at the center in the heightdirection, for holding the rear part of the left guiding shaft 401A,similar to the right frame 301 described above.

[0266] A threaded hole 401F is formed on the front left side wall of theleft frame 401 substantially at the center of the height direction. Ahead of a screw 813, screw-coupling into the hole 401F, and the leftside wall together hold the front portion of the guiding shaft 401A sothat the guiding shaft 401A is supported.

[0267] The lower part of the front left side wall of the left frame 401has a threaded hole 401C formed therein to be screw coupled for fixingthe left frame 401 to the left slide plate 110 (shown in FIG. 8; referto the arrow “D”).

[0268] A holder 401E is formed on the rear right portion of the leftframe 401, at substantially the center in the height direction (refer toarrow “C”), for holding the rear portion of the guiding shaft 401D (FIG.16).

[0269] A threaded hole 401G is formed on the right upper part of thefront wall of the left frame 401. A screw 814 screw couples into thescrew hole 401G, through the through-hole 402A of the left frame lid402, so that the left lid 402 is attached at the front of the left frame401. The left lid 402 holds the front of the guiding shaft 401D.

[0270] A threaded hole 402B is formed on the front of the left frame lid402, to which the screw 815 is coupled through the through-hole 410A22provided on the front wall 410A2 of the left outer housing 410.Accordingly, the front portion of the left frame 401 is fixed to thefront wall 410A2 of the left outer housing 410A via the left frame lid402.

[0271] A screw 816 is screwed into the threaded hole 401I formed abovethe upper portion of the threaded hole 401F of the left frame 401,through the through-hole 410A41 formed on the left side wall 410A4 ofthe left outer housing 410A. Accordingly, the left side of the leftframe 401 is fixed to the left side wall 410A4 of the left outer housing410A.

[0272] A screw 817 is screwed into a threaded hole 401H formed on therear right wall of the left frame 401, through the through-hole providedon the rear wall 410A3 of the left outer housing 410A, so that the rearpart of the left frame 401 is fixed to the rear wall 410A3 of the leftouter housing 410A.

[0273] An upper wall 401J, defined by and connected to the upperportions of the right and left side walls of the left frame 401, isapproximately rectangularly shaped. The front left side of the upperwall 401J is provided with a (vertically extending) circularthrough-hole 401K.

[0274] Under the circular hole 401K is formed an engaging portion 405A4formed on the left objective frame 405A, the engaging portion 405Aopposing the circular through-hole 401K.

[0275] As shown in FIG. 16, the left objective frame 405A includes abody 405A1 shaped cylindrically, a first holding member 405A2 providedon the left side of the body 405A, and a second holding member 405A3provided on the right side of the body 405A1 and extending rearward.

[0276] The inner circumferential surface of the body 405A1 is formed tohold the outer circumference of the objective lens 405C, and is femalethreaded. The male threads formed around the outer circumference of theobjective pressing ring 405B are screwed into the female screw, so thatthe objective lens 405C is held by the body 405A1 and the objectivepressing ring 405B.

[0277] The first holding member 405A2 is formed to slidably hold theguiding shaft 401A (shown in FIG. 15), i.e., such that the leftobjective frame 405A is slidable along the axis direction of the guidingshaft 401A. In more detail, the first holding member 405A2 is providedwith two holders 405A21 and 405A22 projecting from the left edges of thebody 405A1. The holders 405A21 and 405A22 are formed to cover or bracketthe outer circumference of the guiding shaft 401A from the top andbottom sides (vertically) The upper holder 405A21 is provided with athreaded through-hole 405A211, and the lower holder 405A22 is providedwith a threaded hole. The through-hole 405A211, when the left objectiveframe 405 is assembled into the left frame 401, opens upward through anoblong circular hole 401L (refer to FIG. 15).

[0278] Accordingly, (before the screw 819 noted below is tightened) theguiding shaft 401A is held by the holders 405A21 and 405A22 so that thefirst holding member 405A2 is movable along the guiding shaft 401A.

[0279] The second holding member 405A3 is provided with a shaft hole405A31 formed to slidably receive the guiding shaft 401D along its axisdirection therein. Accordingly, the second holding member 405A3 isformed to hold the guiding shaft 401D, such that the left objectiveframe 405A is movable in the axis direction of the guiding shaft 401D.

[0280] Thus, the left objective frame 405A is held movably in theoptical axis direction by the guiding shafts 401A and 401D disposedparallel to each other.

[0281] A screw 819 is screwed into the threaded hole in the holder405A22 via a through-hole 405A211 of the holder 405A21, and the holder405A21 and 405A22 clamp the guiding shaft 401A, so that the leftobjective frame 405A is fixed at the position along the optical axisdirection, held on the guiding shafts 401A and 401D of the leftobjective frame 405A.

[0282] An engaging portion 405A4 is provided on the upper portion of theleft side of the body 405A1 of the left objective frame 405A. Theengaging portion 405A4 includes two protrusions 405A41 and 405A42disposed parallel to each other and extending perpendicular to theoptical axis. A channeled adjustment groove is formed, defined by thetwo protrusions 405A41 and 405A42.

[0283] In order to show adjustment of diopter (calibration) duringmanufacturing or assembly, FIG. 22 illustrates a partially sectionedplan view of the left lens barrel. An arrangement jig 1 is inserted intothe circular through-hole 401K of the left frame 401 for engaging withthe engaging portion 405A4 of the left objective frame. When thearrangement jig 1 is rotated, the left objective frame 405A is movedalong the optical axis so that the location of the left objective lensis arranged. This is performed when the screw 819 is not tightened, orbefore the screw 819 is tightened.

[0284] The arrangement jig 1 includes, as shown in FIG. 22, a jig body1A having a sectional shape of a circle, and an eccentric portion 1B atthe tip of the main body 1A. The eccentric portion 1B is offset to aneccentric position with respect to the shaft of the main body 1A, awayfrom the direction of the center axis of the body 1A. The diameter ofthe eccentric portion 1B is formed a little smaller than that of thebody 1A.

[0285] The body A1 is a separate element that is easily insertable intoand removable from the circular hole 401K. The outer diameter of thebody 1A is slightly smaller than that of the circular hole 401K, so thatwhen the body 1A inserts through the circular hole 401K, while the outercircumference of the body 1A abuts the edge of the inner circumferenceof the hole 401K, and is rotated, the body is rotated about the centerof the body 1A.

[0286] As shown in FIG. 21B, while the body 1A is inserted in thecircular hole 401K and the eccentric portion 1B is engaged with theengagement portion 405A4, when the arrangement/calibration jig 1 isrotated, the eccentric portion 1B rotates about the axis of the jig body1A, resulting in displacing the left objective frame 405A, engaged withthe eccentric portion 1B, in the direction of the optical axis.

[0287] Next, the arrangement of the objective lens at the production orassembly stage of the binocular, using the calibration or adjustment jig1, is described.

[0288] The left objective lens 405C is arranged in the left lens barrel400 of the telescope optical system before the outer housing 410A isattached to the left frame 401 at the production stage.

[0289] As is detailed below, the diopter of the right objective lens ofthe right lens barrel 300 can be corrected for variation between anoperator's left and right eyes after the binocular is assembled at anytime. However, the location of the left objective lens, once correctedat the production or assembly stage, is constructed to be permanentlycorrected (or at least, not to be readily accessible to the ordinaryoperator).

[0290] First, the diopter of the right telescope optical system is“zeroed” or centered (corrected to zero).

[0291] The “zero point” mark 106F of the diopter decorative ring 106 ofthe diopter decorative ring 106 is aligned to the reference mark 102L(Refer to FIG. 4). By this alignment, the right objective frame 305A islocated at the middle point of its adjustable range.

[0292] Next, as mentioned above, the arrangement/calibration jig 1 isused to arrange the location of the left objective frame 405A of theleft lens barrel 400 along the optical axis direction. The position ofthe left objective frame 405A is correct when the diopter adjustment ofthe left and right side are equal to one another (since the useradjustment on the right side is zeroed during the assembly-timeadjustment of the left side). This equality can be optically ormechanically measured or determined by an external tool; the manner ofsuch determination is not critical.

[0293] Subsequently, the screw 819 (as shown in FIGS. 16, 21, and 22) isscrewed and tightened (to a sufficient degree) into the threaded hole ofthe holder 405A22 of the left objective frame 405A, fixing the leftobjective frame 405A to the guiding shaft 401A, and fixing the locationof the left objective frame 405 with respect to the left frame 401,along the optical direction. Accordingly, the location of the leftobjective frame 405A with respect to the left frame 401 along theoptical axis direction, that is to say the location of the objectivelens, is fixed relative to the left frame 401.

[0294] At this point, the user diopter adjustment on the right telescopeoptical system has been zeroed, i.e., in the middle of its adjustablerange. Moreover, the diopter adjustment of the left and right sides isequal. Lastly, the assembly-time diopter adjustment of the lefttelescope optical system is calibrated, complete and fixed at the equaland zeroed position. Accordingly, access by an operator, consumer oruser to the assembly-time diopter adjustment may be prevented,specifically by mounting the left outer housing 410A (as shown in FIG.15) to the left frame 401 and left frame lid 402 via screw 815, 816 and817. Access to the screws 815 and 817 is prevented and the appearance ofthe binocular is improved by securing the left rear cover 410B and leftfront cover 410C via adhesive tape 410D and 410E, respectively.

[0295] In the condition mentioned above, the focus of the right and lefttelescope optical systems are matched so that the full dioptercorrection range (i.e., from zero to an equal degree in “+” and “−”directions) of the right lens barrel with respect to the right lensbarrel can be effectively assured along the optical direction.

[0296] Therefore, the arrangement/adjustment range of the objective lenslocation in the production or assembly stage is calibrated, set andassured by the left lens barrel of the telescope optical system, whilethe arrangement or adjustment range of the diopter correction on usual(operator, consumer, or user) operation can be set and assured by theright lens barrel of the telescope optical system. Accordingly, the sizeof the right and left lens barrel of the telescope optical systems alongthe axis can be formed smaller, i.e., since the two adjustment rangesare not cumulative in one lens barrel, but are separated between the twolens barrels.

[0297] The movable range of the right side first and second lens frames307A and 308B (as well as the left side first and second lens frames407A and 407B) along the optical axis direction is described below.

[0298] As noted, the first and second lens guiding pieces 208 and 209move in opposite directions with each other along the optical axis,slidably disposed respectively on the left and right side of the camring 207 with a predetermined distance therebetween. The cam grooves207D, 207E and engagement of the balls 210B are structured such that themoving ranges of the first and second lens guiding pieces 208 and 209overlap in the longitudinal, optical axis direction. As the first andsecond lens guiding pieces 208 and 209 move, the first and second lenssliders 213 and 214 are moved to approach to/apart from each other alongthe optical axis direction.

[0299] Since the moving ranges of the first and second lens guidingpieces 208 and 209 overlap, the space necessary to the first and secondlens pieces 208 and 209 for moving can be reduced in the optical axisdirection, as well as the size of the cam ring 207.

[0300] Although the moving ranges of the first and second lens guidingpieces 208 and 209 overlap in the optical axis direction, the movingranges of the channels 213D, 214D (which drive the lens frames 307A,308A, e.g., on the right side) and the moving ranges of the lens frames307A, 308A (e.g., on the right side) do not overlap in the optical axisdirection. The relative lengths of the first center portion 213A and theextension 214A1 “remove” the overlap, i.e., the first center portion213A is shortened with respect to the extension 214A1 to offset theright-side moving range of the channel 213D in front of the left-sidemoving range of the channel 214D. The engaging arms 307A2, 308A2, 407A2,and 408A2 also make use of the offset (or optionally additionallyinclude a further offset) so that the first and second lens frames 307A,308A (and 407A, 408A) are movable between a position essentially flushwith each other in the optical axis direction (as shown in FIG. 43) anda position separated from one another by approximately the amount of thecombined movable ranges of the guiding pieces 208, 209 (as shown in FIG.42).

[0301] Therefore, the space required for the first and second lensframes 307A, 308A, as well as the systems for moving them, is furtherreduced in the optical axis direction. Accordingly, the size of zoomingadjustment mechanism and the binocular in the length (front to back)direction is also further reduced.

[0302] The overall operation of the binocular 1000, configured suchmentioned above, is described below.

[0303] The binocular 1000 is, when stored or not used, as illustrated inFIGS. 1 and 2, that is, the right and left lens barrels 300 and 400 areclosed and the right and left eyepiece cylinders 304 and 404 areaccommodated in the body, or drawn in.

[0304] An operator holds the right and left lens barrel 300 and 400respectively with right and left hands, the thumbs of the right and lefthands supporting the right and left outer housing bottoms, and otherfingers of right and left hands hold the upper surface of the upperwallof respective right and left outer housing, therefore, holding the outerhousing between the fingers and thumbs.

[0305] The focus arrangement ring 202 and the zooming arrangement ring204 are disposed on the main shaft 201, adjacent to each other on thecenter of the binocular 1000 in the lateral direction, so that anyfinger (without the use of the thumbs) of the right and left hands caneasily rotate the two rings 202 and 204.

[0306] When the focus arrangement ring 202 is rotated by a finger, thearm 202A1 integrally formed on the body 202A (shown in FIG. 11),extending in the diameter direction, is also rotated, so that the balls203 engaged in the engagement portion 202A11 on the arm 202A1 move alongthe two-stage (coarse and fine) guiding grooves 206A1.

[0307] The protrusions 206C4, 206C5 (shown in FIG. 11) formed on theright and left portion of the flange 206C of the moving shaft 206 movedalong the guiding grooves 101C11 and 101D11 (shown in FIG. 9) extendingalong the right and left wall 101 c and 101D.

[0308] Each protrusion 206C4 and 206C5 abuts the banks 101C12 and101D12, restricting the range of motion of the moving shaft 206 towardthe front, and each protrusion 206C4 and 206C5 abuts the rear wall 101G1of the body 101, restricting the range of motion to the rear.

[0309] As shown in FIG. 11, when the balls 203 move, engaging the firstgroove 206A11 (wide pitch), the moving amount of the moving shaft 206 bya rotation of the focus rotation ring 202, is larger than that whenengaging the second groove 206A12 (narrow pitch).

[0310] The moving shaft 206, coupled with the cam frame 210, isintegrally attached to the pressing plate 215 (shown in FIG. 9). Thepressing plate 215 is further attached integrally with the cooperatingshaft 216. Accordingly, cooperating with the movement of the movingshaft 206, the right and left moving units 303 (shown in FIGS. 5 and 13)and 403 (shown in FIG. 16) move rearward. Consequently, the right andleft eyepiece cylinders 304 (shown in FIGS. 5 and 14) and 404 (shown inFIGS. 5 and 17) project out the binocular. In such a condition, anoperator looks at an object of infinite distance through the botheyepiece 309 and 409 and laterally extends the right and left lensbarrels 300 and 400 to set an appropriate inter pupillary adjustment,such that the right and left images coincide for binocular vision.

[0311] As mentioned above, the right and left outer housing 310A (shownin FIGS. 5 and 12) are respectively fixed to the right and left slideplates 109 and 110 (shown in FIGS. 6 through 8). Therefore, the rightand left lens barrels 300 and 400 move simultaneously and by the samedistance in the lateral direction, approaching to and moving away fromeach other, providing the observer an easy operation for inter pupillaryadjustment. Moreover, due to the protrusions 103D extending from bottomlid 103 the slide plate 110 moves laterally with a given frictionalforce, affording a more comfortable operation feeling for theinterpupillary adjustment.

[0312] With reference to FIGS. 3, 5, and 6, as well as FIGS. 13 and 14,focus is arranged by rotating the focus arrangement ring 202. That is,the rotation of the focus arrangement ring 202 is converted into alinear movement of the right moving unit 303 (shown in FIG. 13), theright eyepiece cylinder 304 (shown in FIG. 14) and the eyepiece unit 309(shown in FIG. 14) with respect to the right objective frame 305A (shownin FIG. 13).

[0313] The prism unit 306 (shown in FIG. 13), the first lens 307 (shownin FIG. 14), the second lens 308 (shown in FIG. 14), and the third lens309 (shown in FIG. 14) move linearly with respect to the objective lens305C (shown in FIG. 13), so that the focus is arranged or adjusted.

[0314] The left lens barrel 400 also has the same operation for focusadjustment, a description of which is accordingly omitted.

[0315] Again, with reference to FIGS. 3, 5, and 6, and in detail shownin FIGS. 9-11, 14, and 38-43, magnifying-power is varied by rotating thezooming arrangement ring 204. That is, by the rotation of the zoomingarrangement ring 204, the main shaft 201 (shown in FIG. 11) rotates,causing the rotation of the cam ring 207 with respect to the cam frame210. The first lens guiding piece 208 and the second lens guiding piece209, engaged respectively with the first cam groove 207D and the secondcam groove 207E via balls 210B in the cam ring 207, are moved in theopposite direction with each other.

[0316] Consequently, the first and second lens frame 307A and 308A (bothshown in FIGS. 14, 42, and 43), being respectively engaged with thefirst and second lens slide plates 213 and 214 (shown in FIGS. 9 and10), are moved to approach/move away from each other (always moving inopposite directions) by the same movement of the first and second lensguiding pieces 208, 209. The first and second lens 307B and 308Bapproach and move away from each other so that the magnifying power ofthe telescope optical system is varied. Also, in the left lens barrel400, which is constructed in the same structure as that of the rightlens barrel 300, the zooming is operated in the same operation asdescribed above.

[0317]FIG. 42 and 43 illustrates a bottom plan view of the opticalarrangement unit. As shown in FIG. 42, the magnifying-power of thetelescope optical system is set to its lowest when the first lens 307Band the second lens 308C are disposed most apart to each other. On theother hand, the magnifying-power of the telescope optical system is setto its highest when the first lens 307B and the second lens 308C aredisposed most close to each other, as is shown in FIG. 43.

[0318] The left lens barrel 400 also has the same operation for zoomingadjustment, a description of which is accordingly omitted.

[0319] Next, the operation of the diopter correction will described withreference to FIGS. 18 through 20, with some details shown in FIGS. 14and 17.

[0320] First, an observer observes a distant object by the left eyethrough the third (eyepiece) lens 409C (shown in FIG. 17) of the leftlens barrel 400, focusing on the distant object so as to see the distantobject most clearly, by rotating the focus arrangement ring 202. Next,observing by the right eye through the third (eyepiece) lens 309C (shownin FIG. 14) of the right lens barrel 300, the observer rotates thediopter decorative ring 106 to see the object most clearly (i.e., in the“+” direction toward the position of FIG. 19, or in the “−” directiontoward the position of FIG. 20).

[0321] That is, rotating movement of the diopter correction decorativering 106, causing rotation of the diopter eccentric seat 107, isconverted to linear motion by engagement of the eccentrically seated (ormounted) disk-shaped body 107A and the channeled adjustment grooveformed by the engaging walls 305A41, 305A41, so that the location of theobjective lens 305 is arranged with respect to the right frame 301 fordiopter correction.

[0322] If the observer is the same upon subsequent uses of the binocular1000, there is no need to change the diopter after the user's initialcorrection. However, each operator can adjust for variation between thatoperator's left and right eyes.

[0323] The diopter correction decorative ring 106 is disposed on thecenter in the width direction near to the front end of the supportingplate 102, so that the thumb of either the right and left hands caneasily operate the diopter decorative ring 106 to rotate. Moreover, thethumb is already at, or is easily moved to, a sufficient distance, whilethe observer is focusing or zooming, from the diopter correctiondecorative ring 106, so that unintentional diopter operation by thethumb is prevented.

[0324] In the binocular according to the present embodiment with respectto diopter adjustment, the first optical system and the second opticalsystem are selected respectively as the objective optical system and theeyepiece optical system. However, the first optical system and thesecond optical system can be respectively selected inversely as theeyepiece optical system and the objective optical system. That is, theadjusting mechanisms, in one embodiment eccentric mechanisms, may alsobe provided in a similar manner to the eyepiece optical system.Moreover, the first optical system may well be selected from a pluralityof optical systems that constitute a portion of the objective andeyepiece optical systems. That is, the adjusting mechanisms, in oneembodiment eccentric mechanisms, may also be provided in a similarmanner to optical systems which share parts among the objective andeyepiece optical systems.

[0325] Although the above description sets forth particular embodimentsof the present invention, modifications of the invention will be readilyapparent to those skilled in the art, and the inventors expressly intendthat the scope of the invention, as well as elements necessary for theinvention to function, be determined solely by the appended claims.Changes may be made, within the purview of the appended claims, asoriginally submitted and as amended, without departing from the scopeand spirit of the invention in its aspects. No one or more of thepreceding described elements is critical to the operation of theinvention, except as explicitly described herein. Although the inventionhas been described with reference to particular means, materials andembodiments, the inventors do not intend that the invention is to belimited to the particulars disclosed; rather, the invention extends toall equivalent and/or insubstantially different structures, methods anduses such as are within the scope of the appended claims, as originallysubmitted and as amended.

[0326] The present disclosure relates to subject matter contained inJapanese Patent Application No. 2000-136602, filed on May 10, 2000,which is expressly incorporated herein by reference in its entirety.

What is claimed is:
 1. A mechanism for moving a first optical elementand a second optical element along an optical axis of an optical system,comprising: first and second guiding shafts disposed parallel to theoptical axis and spaced apart to each other in a direction perpendicularto the optical axis; a first frame movable along the optical axis andsupporting the first optical element, said first frame including firstfront and rear shaft bearings and a second shaft bearing, said firstfront and rear shaft bearings being disposed spaced apart to each otheralong said first guiding shaft and engaged with said first guiding shaftslidably along the longitudinal direction of said first guiding shaft,said second shaft bearing being engaged with said second guiding shaftslidably along the longitudinal direction of said second guiding shaft;and a second frame movable along the optical axis and supporting thesecond optical element, said second frame including third front and rearshaft bearings and a fourth shaft bearing, said third front and rearshaft bearings being disposed spaced apart to each other along saidsecond guiding shaft with said second shaft bearing therebetween andengaged with said second guiding shaft slidably along the longitudinaldirection of said second guiding shaft, said fourth shaft bearing beingengaged with said first guiding shaft slidably along the longitudinaldirection of said first guiding shaft between said first front and rearshaft bearings.
 2. The mechanism according to claim 1 , wherein saidfirst front and rear shaft bearings are provided with a first front holeand a first rear hole, respectively, into which said first guiding shaftis inserted, said first front and rear holes are formed to receive saidfirst guiding shaft without play within a plane perpendicular to theoptical axis, and said second shaft bearing is provided with a secondhole into which said second guiding shaft is inserted, said second holeis formed to receive said second guiding shaft with play in a directionsubstantially perpendicular to the optical axis.
 3. The mechanismaccording to claim 2 , wherein said second hole has a rectangularcross-section of which longitudinal direction is substantiallyperpendicular to the optical axis.
 4. The mechanism according to claim 2, wherein said third front and rear shaft bearings are provided with athird front hole and a third rear hole, respectively, into which saidsecond guiding shaft is inserted, said third front and rear holes areformed to receive said second guiding shaft without play within a planeperpendicular to the optical axis, and said fourth shaft bearing isprovided with a fourth hole into which said first guiding shaft isinserted, said fourth hole is formed to receive said first guiding shaftwith play in a direction substantially perpendicular to the opticalaxis.
 5. The mechanism according to claim 4 , wherein said fourth holehas a rectangular cross-section of which longitudinal direction issubstantially perpendicular to optical axis.
 6. The mechanism accordingto claim 1 , wherein said first frame has a first extension extendingparallel to said first guiding shaft between said first front and rearshaft bearings to support said first rear shaft bearing spaced apartform said first front shaft bearing.
 7. The mechanism according to claim6 , wherein said first extension has an abutting portion against whichsaid fourth shaft bearing abuts to align said fourth hole with saidfirst front hole and said first rear hole.
 8. The mechanism according toclaim 6 , wherein said second frame has a second extension extendingparallel to said second guiding shaft between said third front and rearshaft bearings to support said third front shaft bearing spaced apartfrom said third rear shaft bearing
 9. The mechanism according to claim 8, wherein said second extension has an abutting portion against whichsaid second shaft bearing abuts to align said second hole with saidthird front hole and said third rear hole.
 10. The mechanism accordingto claim 1 , wherein said first and second guiding shafts are arrangedon a plane including the optical axis.
 11. The mechanism according toclaim 1 , wherein each of said first and second optical elements is anoptical lens.
 12. The mechanism according to claim 1 , wherein saidfirst and second optical elements are lenses of a telescope opticalsystem of which magnifying power varies when distance between said firstand second optical elements along the optical axis is changed.